March 2​: Full Moon ​​

​March 15: The planet Mercury will be at greatest eastern elongation - 18.4 degrees from the Sun. This is the best time to view Mercury because it will be at its highest point above the horizon in the evening sky. Look for the planet low in the western sky just after sunset.

March 17New Moon

The Moon is on the same side of Earth as the Sun and won't be in the night sky. With no moonlight to interfere this is the best time of the month to observe faint objects such as galaxies and star clusters.

March 20: Spring Equinox

The Sun will shine directly on the equator and there will be nearly equal amounts of day and night throughout the world.

March 31: Full Moon

​The second full moon in the same month is sometimes referred to as a blue moon. This year is particularly unique in that January and March both contain two full moons while February had no full moon.

Helioseismology & SOHO 

8/11/17 Space.com & NASA

The Sun's Core Rotates Four Times Faster Than the Solar Surface

Visualize the Total Solar Eclipse with NASA's 3D App

China's Tiangong-1 Space Lab to Fall to Earth by April 2018

How to Shoot (Photograph) a Solar Eclipse
By Keith Harrod

Pick up the August issue of Sky & Telescope magazine. See the article written by Dennis di Cicco that starts on page 14. I highly recommend that and other articles in that issue

How Far Can Amateur Astronomers See?

6/1/2017     By Keith Harrod

That’s a question I often get asked on club public nights. The answer is: It depends on several factors.

The first factor is if the observation is being done by eye or as a long exposure photograph.

For the purposes of this article I’ll only consider observing by eye. Doing amateur astrophotography is a specialty pursued by fewer amateur astronomers than looking through a telescope by eye.

The next factor is how much light the telescope being used can gather.  The wider the diameter of the primary optic (lens or mirror) the telescope has, the further we can see.

At the smaller end would be telescopes like 60 mm (2.36 in) telescopes that have a limiting apparent stellar magnitude of about magnitude 11.5.

A 305 mm (12 in) optic has a limiting apparent stellar magnitude of about magnitude 15.

Note that as a round primary optic’s diameter increases the area of the primary optic increases as square function. If you double the optic’s diameter the primary optic now gathers 4 times more light. On that basis a 120 mm (4.7 in) primary optic has a limiting apparent stellar magnitude of about magnitude 13.

 Important factoid: The magnitude scale is logarithmic; so a + or - difference of one magnitude corresponds to a change in brightness by a factor of 5√100, or about 2.512 times.

The next factor is if the object being seen is a point light source, like stars, or an extended light source, like a galaxy or a planetary nebula.

In the case of extended light sources a better number that describes how readily seen it is is its surface brightness. Surface brightness is usually quoted in magnitudes per square arcsecond. So a distant galaxy may have an apparent magnitude of 7, right at naked eye visibility under truly dark skies, yet have a surface brightness of only 13 and actually barely visible in a 6” (152 mm) telescope.

The last factor is how dark the night sky is wherever it is you are observing. Without a doubt, the darker the sky is the further we can see.

Because of light pollution, few people today know what a truly dark night sky looks like. Where I live in rural Iowa the night sky is graded as a Class 4, Urban/Rural transition zone according to the nine-level, numeric Bortle Scale of light pollution. Light pollution domes are visible in several directions from our club observing site – Dean Memorial Observatory.

The closest Class 1 sky to me is an almost 8 hour drive west to a sparsely inhabited part of Nebraska.

Lastly, the Moon and its phase also affects how far we can see. We can see the furthest when the Moon is New because the Moon sets close to the same time as the Sun then and is not in the night sky.

If the sky is dark enough and one has a large enough telescope (6” or bigger), the furthest most northern hemisphere amateur astronomers can see is an object some 2.3 billion light years away, the quasar 3C 273 in Virgo. 3C 273 has an apparent magnitude of 12.9.

The term "quasar" originated as a contraction of "quasi-stellar radio source", because quasars were first identified by radio telescopes as sources of radio emission. Looking at visible wavelength photographs of the night sky at the location the radio sources were at showed quasars resembled point-like stars.

If 3C 273 was just 33 light years away, instead of 2.3 billion light years away, it would be as bright in the sky as our Sun that is only 8.3 light minutes away. Put another way 3C 273 is over 4 trillion times more luminous than the Sun at visible wavelengths of light.

The Fastest Man Made Object - Ever
2/28/2017     By Keith Harrod

Solar Probe+ (or Solar Probe Plus)

Launch window: July 31 - August 19, 2018

The Solar Probe+ spacecraft will attain a velocity of 120 mi/sec (432,000 mi/hr), way faster than the current fastest man-made object -  the Juno orbiter - that reached a speed of 36.1 mi/sec (130,000 mi/hr) just before Juno was inserted into Jupiter orbit.

Once on station Solar Probe+ will orbit the Sun at about 8.5 solar radii, or about 3,700,000 mi (6,000,000 km) from the Sun. At that distance the incident solar intensity is approximately 520 times the intensity in Earth orbit.

The spacecraft will use a reinforced carbon-carbon composite solar shadow-shield to protect spacecraft systems and the scientific instruments.

A primary photovoltaic array will be used for the part of the mission further out from the Sun than 0.25 AU (23,250,000 miles). At 0.25 AU the primary power system will be retracted behind the shadow shield, and a secondary array that uses pumped-fluid cooling to maintain operating temperature will be used from there to close approach.

Solar Probe+ is designed to investigate the Sun's Corona in an effort to determine

• What mechanism(s) accelerate and transport the energetic particles that make the Corona so very much hotter than the Sun's surface.

• How the Corona accelerates the solar wind.

• Examine the structure/dynamics of magnetic fields at the sources of the solar wind.

•  Explore dusty plasma near the Sun and its influence on solar wind and energetic particle formation.

Getting the Solar Probe Plus spacecraft close to the Sun will require several repeated gravity assists at Venus to incrementally decrease the spacecraft's orbital perihelion.


How To: Become A Better Astronomer
10/7/2016     By Keith Harrod

The key is  knowing the constellations.

Many think learning the constellations is a huge, hard task, and it is, if you try to learn all the constellations, and do it all in one sitting.

It’s not hard if we analyze what we actually need to do.

Those of us living in mid-northern latitudes can’t see all 88 constellations, unless we occasionally travel to the equator or further south.

From mid-northern latitudes we can only see about 37 of the constellations, and of those, we can see 6 (the circumpolar constellations) year round. Which of those 6 we can see depends on what time of night you’re looking at the sky.

Plus, observing lower than about 20° above the horizon yields compromised views for a variety of reasons, mostly because we are looking through too much of our atmosphere, and to a lesser extent because of light pollution domes and other light pollution near the horizon. So it's nice to know which constellations near the horizon we can see parts of, but they aren't reasonably part of what we can observe well.

Next, we can take advantage of the fact our planet orbits our Sun such that just under  ½ of the non-circumpolar constellations can’t be seen at any given time on any given night, and the constellations we can see slowly drift across the night sky.

Of course today we have computers, the Internet, and planetarium apps  so we don’t even need night to look at a representation of the night sky and the constellations on our computers, laptops, tablets, or smart phones.

I use Stellarium, a free to download online planetarium application, a lot.

But let’s not forget that amateur astronomy is usually an outdoor nature hobby and when night skies are clear enough, getting outside and looking at the sky has its own rewards.

If you’re outside using your naked eye, binoculars, or a telescope having a good sky atlas really helps.

There are cell phone apps that can show small, but scrollable, portions of the night sky, but there is a lot to be said for having a good hard copy sky atlas.

Sky & Telescope’s Pocket Sky Atlas, the original or the new Jumbo version, is very popular, and the next level of detail many use is a version of Sky Atlas 2000.0. I use the laminated Field version of Sky Atlas 2000.0, both at home in the daytime and at observing sites at night.

Today, many new to doing astronomy that are thinking of buying a telescope, and that have the means to, seem to gravitate to a computerized telescope. I would suggest that letting a computerized telescope do all the work of locating things in the sky short circuits learning the constellations and thus hinders being a better amateur astronomer. By all means, if you can afford a computerized GoTo telescope, get one. However, I recommend learning the constellations well none the less.

Terence Dickinson and Alan Dyer say in their Backyard Astronomer's Guide, "A full appreciation of the universe cannot come without developing the skills to find things in the sky and understanding how the sky works. This knowledge comes only by spending time under the stars with star maps in hand."


The Brightest Observed Stellar Event in Recorded History.
9/17/2016     By Keith Harrod

April 30, and May 1, 1006 a "guest star", probably a Type Ia supernova, was described by observers across China, Japan, Iraq, Egypt, and Europe.

Modern astronomers estimate its distance from us at about 7,200 light-years (2.2 kpc, or kiloparsec) and we now call the remnant of the event SN 1006, or the supernova of 1006.

Commentary in 1006 stated the event was some 16 times brighter and about 3 times bigger in the sky than Venus. Observers noted that the new star was low on the southern horizon in the constellation of Lupus. Monks at the Abbey of Saint Gall in Switzerland - latitude  47.5° North - recorded the most northerly reported sighting. A petrogylph in the White Tank Mountain Regional Park, in west-central Maricopa County, Arizona, has been interpreted as a representation of the supernova.

There appear to have been two distinct phases in the early evolution of this supernova. The first three-month period at which it was at its brightest; it then diminished, and brightened again for a period of about eighteen months.

The associated supernova remnant from this explosion wasn’t identified until 1965. Observations of the supernova remnant in visual, x-ray and very-high-energy gamma-ray emission over the next few years showed no remaining neutron star or black hole, the usual situation expected for a Type Ia supernova.

Consequently, given that no companion star remnant has been found there, a mechanism strongly suggested for triggering SN 1006 is the merger of two white dwarfs. If that is what happened their combined mass would be expected to exceed the Chandrasekhar limit of about 1.4 solar masses . The resulting merger is then called a super-Chandrasekhar mass white dwarf. We have only scratched the surface regarding understanding how the Universe works.

It is worth noting that research has suggested that Type Ia supernovae can irradiate the Earth with significant amounts of gamma-ray flux, a threat to the Earth's protective ozone layer, producing effects on life and climate from up to distances of about 1 kiloparsec (kpc) from Earth. While SN 1006 at 2.k kpc away did not appear to have significant effects on Earth’s ozone layer, a signal of its gamma-ray flux outburst can be found recorded in nitrate deposits in Antarctic ice.

The Chandra X-ray Observatory made an image of the associated supernova remnant of SN 1006 on September 30, 2008, at 06:35:19.


Our Place in the Milky Way

September 13, 2016     By Keith Harrod

 Our Sun, and our solar system, orbit the Milky Way galaxy once every 225 to 250 million years.

Our orbit around the Milky Way is roughly elliptical with gravitational perturbations caused by galactic spiral arms and non-uniform mass distributions we encounter on each orbit. The Sun also oscillates up and down relative to the galactic plane approximately 3 times per orbit. We orbit the Milky Way at a speed of about 220 km/s. We are currently moving towards the star Vega near the constellation of Hercules, at an angle of roughly 60 sky degrees to the direction of the Galactic Center, and since the origin of humans have completed about 1/1250 of a revolution. In its 4.6 billion year lifetime the Sun has made some 18 to 20 orbits of the Milky Way.

These days’ astronomers think the Sun lies on a spur close to the inner rim of the Milky Way's Orion-Cygnus Arm, though I have to mention that the Milky Way's spiral structure is uncertain, and there is currently no consensus among astronomers on the layout of the Milky Way's spiral arms.

Using different techniques we've come up with an approximate range indicating we are 26,000–28,000 light-years (8.0–8.6 kpc , or kilo parsecs) from the Galactic Center. (Note: A parsec is 3.26 light-years, so a kpc is 3260 light-years)

But let’s look at our more local surroundings.

Astronomers think our Sun is close to the edge of what is known as the Local Interstellar Cloud, or LIC. An interstellar cloud is the generic name given to an accumulation of gas, plasma, and dust in galaxies. Put another way, an interstellar cloud is a denser-than-average region of the Interstellar Medium (ISM).

The next closest star, Proxima Centauri, is in an interstellar cloud which is called the G-Cloud. Our Sun may be so close to the edge of the LIC we are in a region where the LIC is interacting with the next door G-Cloud. It may be worth noting that Proxima Centauri is just 4.2 light-years away, while the star Altair, 17 light-years away is also in the G-Cloud.

(Here in northern latitude Iowa, Proxima Centauri is always below the horizon. The closest star we can see, 6 light-years away and also in the G-Cloud, is Bernard's Star in Ophiuchus.)

Moving out a bit further we think the LIC and the G-Cloud are embedded in what’s known as the Local Bubble. The Local Bubble is a cavity in the interstellar medium (ISM) in the Orion-Cygnus Arm of the Milky Way. The local bubble is at least 300 light years across and has a density approximately one tenth of the average for the ISM in the Milky Way (0.5 atoms/cm3), and one sixth that of the Local Interstellar Cloud (0.3 atoms/cm3).

Our Solar System has been traveling through the region currently occupied by the Local Bubble for the last five to ten million years. The Local Bubble is not spherical, but seems to be shaped like an hourglass. It is up against other bubbles of less dense interstellar medium (ISM), including, the Loop I Bubble, the Loop II Bubble and the Loop III Bubble.

They’re pretty sure the Loop I Bubble was created by supernovae and stellar winds in the Scorpius–Centaurus Association of OB stars, some 500 light years from the Sun. The star Antares, one of the largest, most luminous observable stars and a member of the Scorpius–Centaurus Association of OB stars, is in the Loop I Bubble.

So it turns out that for doing astronomy we are fortunate to currently be amongst all these bubbles and not in a part of the Milky Way jamb-packed and densely populated with stars and galactic dust and gas.

Additional Reading:






Juno’s Next Close Approach
8/24/2016     By Keith Harrod

  The NASA Jupiter probe Juno is about to complete the 1st of 2, 53-day orbits. Juno’s first orbit began this last July 4 after a trip from Earth that commenced on Aug. 5, 2011. On August 27, 2016 Juno will approach to within just 2,600 miles (4,200 km) of Jupiter’s cloud tops near Jupiter’s North Pole.

Juno team members at NASA's Jet Propulsion Laboratory in Pasadena, California have said the Aug. 27 pass should return the first real scientific bounty of the mission. Rick Nybakken, Juno project manager, said, "We're in an excellent state of health, with the spacecraft and all the instruments fully checked out and ready for our first up-close look at Jupiter."

Juno is on a $1.1 billion mission to map out Jupiter's magnetic and gravitational fields, among other goals. Juno was sent to Jupiter to gather scientific data that will be used to determine the planet's interior structure and composition. The scientific data should also help us understand Jupiter's formation and evolution. Understanding Jupiter's formation, evolution, interior structure, and composition should help researchers learn more about how the solar system itself came together.

Juno’s science mission will officially begin when Juno will perform one more engine burn on October 19 to shift Juno into a 14-day orbit at the end of the 2nd 53 day orbit. The engine burn is needed to shift Juno into a 14-day orbit. The about 2,000 kilometer close approach on each subsequent 14-day orbit is necessary for the key data gathering phase of the mission. Juno will complete 37, 14 day orbits.

The 14 day orbits also minimize Juno’s contact with Jupiter's dense radiation belts that can damage spacecraft electronics and solar panels. Juno is equipped with a 1-centimeter-thick, titanium walled, “radiation vault” that protects and shields Juno's electronics from Jupiter’s intense fields of radiation.

At the end of the 37, 14-day orbits Juno will perform a controlled deorbit so Juno isn’t left as orbiting debris, and to minimize risks of contamination in accordance with NASA's Planetary Protection Guidelines.

Juno principal investigator Scott Bolton, of the Southwest Research Institute in San Antonio, said "For five years, we've been focused on getting to Jupiter. Now we're there, and we're concentrating on beginning dozens of flybys of Jupiter to get the science we're after."

Additional Reading:




Great Mid-Summer Globular Cluster Show

8/7/2016    By Keith Harrod

This time of year there are a lot of globular clusters to look at in the night sky.
Sagittarius alone has 6 Messier globular clusters- M22, M28, M54, M55, M70, & M75.
And even more NGC globulars - 6440, 6522, 6528, 6540, 6544, 6553, 6558, 6569, 6638,  6642, & 6723.

Other Messier globular clusters to look at in August:

M2, M3, M4, M5, M9,

M10, M12, M13, M14, M15, M19,

M56, M62, M71, M80, M92, M107.

M54 is quite interesting.
Charles Messier discovered M54 in 1778.
It had long been thought M54 was here in the Milky Way about 50,00 light-years from Earth. It was determined in 1994 that M54 isn't likely in the the Milky Way but is a globular cluster that belongs to the Sagittarius Dwarf Elliptical Galaxy (Sgr dSph) one of the Local Group of galaxies and until recently thought to be the closest of the local group to the Milky Way.

Indeed many astronomers think M54 is the core of the Sgr dSph, and in 2009 a team of astronomers reported they had detected an intermediate black hole at the core of M54.

Messier globulars just visible with the naked eye, under very good sky conditions - truly dark, crystal clear, rock steady - and even then they will be faint.
M2, M5, M13, M15.
If conditions are less than good, use a binocular.

Additional Reading:

Globular cluster


Time To Make Plans

7/22/2016     By Keith Harrod

Next month, August, Earth will again pass through the debris from the tail of comet Swift-Tuttle as it does every mid-July through mid-August.

This year Earth will pass through the densest, dustiest part of Swift-Tuttle debris on August 12. You can still catch some good meteor action from the famed meteor shower several days before and after the 12th.

With a radiant in the constellation Perseus the Perseid meteor shower is very popular and usually puts on a nice show.

NASA meteor expert Bill Cooke predicts this year's Perseid meteor shower show will be as good as the 'outburst' shower we had in 2009 with double the usual rate of 80 or so meteors per hour with up to 200 meteors per hour.

Check moonset times to have the darkest sky on the nights you want to watch the show and the best time is after midnight because we are then 'over the hump' and the sky is

leading Earth's movement as Earth rotates on it's axis.

Additional Reading:



More Juno News

7/16/16     By Keith Harrod

Now that Juno is safely in orbit at Jupiter, 5 of the 7 science gathering devices on the Juno Jupiter orbiter have been turned on in anticipation of Juno's next close approach to Jupiter on August 27.
The science devices were left off during orbit insertion as a way to simplify the orbit insertion procedure.
A brief mid-orbit engine burn is scheduled to fine tune the parameters of this first of two 57 day orbits.
There will be just the two 57 day orbits, and then another engine burn will put Juno in a 14 day orbit. The mission plan calls for 35, 14 day orbits.
A special titanium vault had to included in Juno's design to protect the science instruments from Jupiter's strong magnetosphere and the radiation the magnetosphere traps.

To learn more about Juno's design and mission: visit:https://www.missionjuno.swri.edu/spacecraft/juno-spacecraft


Juno - Update

From: http://www.space.com/33326-nasa-juno-jupiter-probe-autopilot.html

7/1/16  By Mike Wall, Space.com Senior Writer   

​​"NASA's Juno spacecraft is now flying solo ahead of its highly anticipated July 4 entry into Jupiter orbit.

On Thursday afternoon (June 30), Juno's handlers sent a command to the spacecraft known as "ji4040," which is designed to transition the probe into autopilot mode, NASA officials said.

"Ji4040 contains the command that starts the Jupiter orbit insertion sequence," Juno mission manager Ed Hirst, of NASA's Jet Propulsion Laboratory in Pasadena, California, said in a statement. "After the sequence executes, Juno is on autopilot."

"If that doesn't all go just right, we fly past Jupiter," Juno principal investigator Scott Bolton, of the Southwest Research Institute in San Antonio, said during a news conference Thursday."


"Juno is currently about 534 million miles (860 million kilometers) from Earth, which explains why JOI cannot be controlled from Earth as it happens. It takes light 48 minutes to travel this distance — longer than the duration of the Jupiter orbit insertion (JOI) sequence 35-minute engine burn.


​Juno - It's Almost There

6/22/2016     By Keith Harrod

On August 5, 2011 NASA launched an Atlas V rocket that was powered by a Russian designed and built RD-180 main engine that boosted the JUpiter Near-polar Orbiter (Juno) out of Earth's atmosphere and on a trajectory that would start a 59 month, 18.7 AU; 1.74 billion mile journey to Jupiter.

In Greco-Roman mythology the god Jupiter drew a veil of clouds around himself to hide his mischief from his wife, the goddess Juno. His wife was able to peer through the clouds and see what Jupiter was up to - his true nature.

Juno is only the second spacecraft to orbit Jupiter. The Galileo probe orbited Jupiter from 1995–2003 on an extended mission. Galileo was hindered because it's main antenna did not deploy as planned, but workarounds allowed Galileo to get us lots of new information about Jupiter and Jupiter's moons over a longer period than originally planned. 

Juno will go into orbit around Jupiter in just a few more days, on July 4, 2016.​ The orbital insertion maneuver will take JUNO very close to Jupiter - 2,672 mi. Closer than any other spacecraft has orbited Jupiter.

Here on Earth we live in a 0.3 rad background radiation environment. Juno is expected to be exposed to 20,000,000 rad when it is closest to Jupiter during the orbit insertion sequence.

Unlike Galileo, Juno will be placed in a polar orbit to study Jupiter's composition, gravity field, magnetic field, and polar magnetosphere. Juno will also search for clues about how Jupiter formed, including whether it has a rocky core, the amount of water present within the deep atmosphere, how its mass is distributed, and its deep 300 mph+ winds.

The orbit insertion burn will put Juno in a 53-day orbit. Juno will do two of those orbits before performing another burn on 19 October that will bring Juno into a 14-day polar orbit. Juno will make 35 of the 14-day orbits. The 37 orbits will take 20 months and the Juno mission will end in February 2018.

​At the end of the mission Juno, like Galileo, will be de-orbited so it will burn up in Jupiter's outer atmosphere to avoid the possibility of impact and biological contamination of one of its moons.

Additional Reading:


NASA’s Juno Mission 25 Days from Jupiter


Three Types Of Twilight

6/9/2016     By Keith Harrod

Twilight is between dawn and sunrise, and between sunset and dusk.

There are three established, widely accepted subcategories of twilight:

• Civil twilight (brightest)

• Nautical twilight

• Astronomical twilight (darkest)

Where the geometric center of the Sun is relative to the horizon is what determines twilight type. 

The apparent travel of the Sun occurs at the rate of 15 degrees per hour (360° per day). Sunrise and sunset typically happen at oblique angles to the horizon so the actual duration of any of the 3 twilight periods will be a function of that angle. The more oblique the angle, the longer a twilight period is. The angle of the sun's motion with respect to the horizon changes with latitude as well as the time of year. In other words the angle of the Earth's axis with respect to the Sun changes through out the year. The exact times for each will vary throughout the year and the times for each are longitude and latitude (where you are) dependent. Also if you are at 48.5° or more latitude different rules apply.

For doing astronomy we want to be aware of when astronomical twilight starts and ends. Astronomical twilight starts in the morning when the geometric center of the Sun is 18° below the eastern horizon. Astronomical twilight ends in the evening when the geometric center of the Sun sinks to 18° below the western horizon.

Most casual observers consider the entire sky fully dark even when astronomical twilight is just beginning in the evening, or is just ending in the morning because many of the brighter stars are visible in the sky.

These days, from where I am in central Iowa, I can usually see Jupiter in the sky right before or just after sunset, but in my telescope Jupiter looks best when the sky is quite a bit darker. As twilight progresses stars become visible by brightness with the brightest stars visible first. Of course those living in or near a city are at a disadvantage because of light pollution as twilight progresses.

Amateur astronomers can easily make observations of point sources, such as stars, before astronomical twilight ends. But critical observations of faint diffuse items, like nebulae and galaxies, often require that the Sun be more than 18° below the horizon and well beyond the limit of astronomical twilight either after sunset or before sunrise. Of course if the moon is up observing the faint stuff is iffy regardless.

Additional reading:

International Dark Sky Association



Zodiacal Light


Sunrise, sunset, day length, twilight, solar noon times web page


Goof Is A Gain - Maybe

6/8/2016     By Keith Harrod

Apparently the Green Castle Recreation Area web site said we were having a Public Night tonight - Wednesday June 8.

June 8 was an error and was supposed to say July 8.

However if the clouds clear, at least one of us club members will be at the club's GCRA site by 8:45 PM with a telescope we can set up. We will certainly talk astronomy with anyone that shows up - clouds or no clouds.

6/9/16 - Jim and I were there but no one else showed up because it was cloudy.

Saturn Opposition Friday, June 3

5/31/2016     By Keith Harrod 

Earth will pass directly between the Sun and Saturn just a few days from now on Friday June 3, at 01:25 AM CDT (06:25 UTC) here around Marshalltown, IA.

Saturn is in the constellation of Ophiuchus and is following Mars in the night sky. Mars moved from Scorpius into Libra last Saturday.

At our latitude and longitude Saturn will be highest in the sky, 27° above the southern horizon the early morning of June 3 at 1:09 AM CDT,  I don't often look at anything lower than 30° above the horizon but this year 27° above the horizon is as high as Saturn is going to get. So it's worth looking at Saturn at it's closest approach to Earth this year.

Saturn has a mean radius of 36,103 miles compared to Jupiter's mean radius of 43,344 miles. With Jupiter at close to 5 AU from the Sun, Saturn is 10 AU from the Sun.

(1 AU = the average distance of the Earth from the Sun - about 93,000,000 miles)

Consequently smaller than Jupiter and further away from us, observing Saturn is more challenging.

Saturn only has one-eighth the average density of Earth. But with its very much larger volume Saturn is just over 95 times more massive than Earth.

Not counting all the moonlets that make up Saturn's ring system Saturn has Saturn has 65 known moons but only 53 of those moons have been given an official name. Saturn's largest moon, Titan, is the 2nd largest moon in the solar system and is the only moon in the Solar System to have a substantial atmosphere. Jupiter's largest moon, Ganymede, is the solar systems largest moon. Both Titan and Ganymede are larger than the planet Mercury.

Additional reading:







Mars Opposition Sunday, May 22

5/20/2016     By Keith Harrod   

Earth will be opposite Mars on Sunday May 21.

Mars opposition occurs on an approximate 26 month cycle, so it will be a bit more than 2 years to the next Mars opposition. The Mars opposition in 2003 was the closest approach in some 10s of thousands of years. The next record setting close opposition with Mars will happen in 271 years.

Mars is visibly reddish to the naked eye and low near the horizon in the southeast part of the sky about 1/2 hour after sunset - if you don't have anything blocking the view.

Mars is only 1/2 as big as Earth, so it is hard to see much detail on Mars when we look at it through a telescope. This opposition, and through the rest of spring, summer, and fall, Mars will stay fairly low in the sky and we will have to look at Mars through extra atmosphere compared to looking straight up. That will also make it hard to see surface detail on Mars.

Mars takes almost 2 earth years (668.6 sols, or solar days) to orbit the Sun once. Of course a 'year' is how long a planet takes to orbit the Sun once. So each planet's 'year' is shorter (if closer to the Sun) or longer (if further from the Sun) than Earth's 'year'. Jupiter's year is equal to 11.86 Earth years.

A bonus for those first astronauts that land on Mars is that a Mars day (a sol) is close to the same 24 hour day here on Earth (also 1 sol). By comparison a sol (day) on Jupiter is a lot shorter than an Earth day at 9 hours 55 minutes and 30 seconds Earth time. A sol on Venus (243 earth days) is longer than a year on Venus (224.7 earth days). Another Venus tidbit is that if one could see the Sun through Venus' miles thick clouds, the Sun would rise in the west and set in the east. Venus is the only planet in our solar system that rotates clockwise on it's axis.

Additional reading:







Hit Me With Your Best Shot

5/18/16     By Keith Harrod

A disproportionately large number of asteroids apparently collided with the early terrestrial planets in the inner Solar System, including Mercury, Venus, Earth, and Mars during an event thought to have occurred approximately 4.1 to 3.8 billion years (Ga) ago. The event, called the Late Heavy Bombardment, happened after the Earth and other rocky planets had formed and accreted most of their mass, but the time was still very early in Earth's history.

It's easy to see evidence that early in the solar system's history there were a lot of big impacts on the Moon back some 3.9 or so billion years ago. The big impacts pierced the Moon's surface and created fissures that allowed volcanic action to let still molten sub-surface material rise to the surface and fill the impact craters the big impacts formed.

Today those big impact craters are large dark areas we see on the moon that we call mare.

While it is likely Earth was also hit by large bodies of left over solar system forming material, Earth is constantly much more geologically active than the Moon ever has been. Those continual geologic processes have left scant evidence of any of those big, early impacts on Earth.

The oldest, and biggest, ancient impact crater we know of on Earth is the 2.02 billion year old Vredefort crater in South Africa. Scientist estimate the Vredefort crater was 185 miles wide back then and was caused by the impact of an asteroid bigger than South Africa's Table Mountain.

Researchers are looking at evidence recently discovered in ancient sediments in Australia that seems to show that a mega asteroid likely between 12 and 19 miles (20 to 30 kilometers) across slammed into the primeval Earth 3.5 billion years ago. That is a much bigger asteroid than the estimated 6 mile wide asteroid or comet that caused the Chicxulub impact that happened about 66 million years ago. The Chicxulub impact is thought to have been the primary cause of the extinction of dinosaurs.

For more information visit:








Bolshoi Teleskop Azimutalnyi (BTA-6)Adaptive Optics (AO)

5/1/16 By Keith Harrod

Adaptive optics have been around for many years.

The Fred Lawrence Whipple Observatory's Multiple Mirror Telescope operated between 1979 and 1998 with 6, round, 1.8 meter mirrors. That gave the MMT the equivalent light gathering area of a 4.5-meter telescope, the 3rd largest optical telescope in the world at the time of it's dedication.

The MMT and the Russian Bolshoi Teleskop Azimutalnyi (BTA-6) helped usher in a new era and a different type of big telescope - a big telescope that used an Altitude/Azimuth mount instead of an Equatorial mount. All major telescopes have since had Alt/Az mounts.

In addition the MMT was different in that it's entire building rotated, offices and all, not just an enclosure over the telescope.

Several technologies pioneered at the MMT contributed to the success of the subsequent generation of large telescopes: high dynamic-range servos for the alt-azimuth mount; highly accurate pointing eliminating the need for sky charts; co-alignment and co-phasing of multiple telescopes; improvements to optical performance by attention to the thermal environment of the facility; contributions to vacuum coatings deposition, optics cleaning, and maintenance; and early experiments in co-phased adaptive optics.

I visited the MMT in the late 1980's. Attention to the thermal environment of the telescope was evident in that the telescope's framework was wrapped with reflective aluminum foil to help control IR emissions. An unanticipated bonus on that visit was discovering that the Coke machines at the MMT were still stocked with 'old Coke' which was replaced in 1985 by a reformulated 'New Coke'. I bought as many cans of old Coke as I could. New Coke failed miserably and went away in 2002.

These days adaptive optics are stepping up to the next level.

Many of the major observatories have been using single lasers to create artificial stars in the atmosphere that are used to monitor atmospheric turbulence so computers can adjust the adaptive optics to cancel out the blurring effects of the roiling atmosphere. However, with a single laser the sampling is a cone in the sky that offers less and less accuracy at higher altitudes. 

Even with the limitations a single AO laser offers, many of the major ground based telescopes using AO today make images that surpass the quality of Hubble Space Telescope images. 

On Tuesday, April 26, 2016 the Four Laser Guide Star Facility for the adaptive optics system on the European Southern Observatory's Very Large Telescope in Chile was activated for the first time. The system uses 4, 22-watt, sodium lasers to cause sodium atoms in the upper atmosphere, up about 90 kilometers, to fluoresce to be used as 4 artificial stars. 

Now they can sample a column of atmosphere so they have better data for the AO computers and even less blurry images.

For more information visit:






More Company

4/14/16      By Keith Harrod

Our Milky Way galaxy now has 49 known satellite companion galaxies.

The 2 brightest of the 49 are visible in southern skies - the Large and Small Magellanic Clouds.

Number 49 was recently discovered in the Crater constellation.

Named the Crater 2 Dwarf galaxy the newly discovered galaxy is quite faint and not visible to our eyes even though it is the 4th largest of the 49 known Milky Way satellite companion galaxies. 

For more information visit: NewScientist.com


Celestial Navigation
4/10/16     By Keith Harrod

In 2006 the US Naval Academy in Annapolis, Maryland ended celestial navigation training. The Navy ROTC had ended celestial navigation training in 2000.

Although this training used to be standard in the U.S. Navy, the advent of GPS technology so simplified and improved the ability to find a ship's position at sea the Navy decide to stop teaching celestial navigation.

In 1978, NASA scientist Donald J. Kessler described a scenario in which the density of objects in low Earth orbit (LEO) could get high enough that collisions between objects could cause a cascade, an ablation cascade - each collision generating space debris that increases the likelihood of further collisions. One implication is that the distribution of debris in orbit could render space activities and the use of satellites in specific orbital ranges unfeasible for many generations.

Of course a US adversary might seek to gain an upper hand by blinding US GPS satellites. US Naval ships at sea would need a way to get an accurate fix of their position . . . without the use of modern technology regardless how the GPS satellites suddenly became unavailable.

The United States Navy recognized those modern vulnerabilities and the Naval Academy has subsequently just recently decided to resume training officers in the 'lost art' of celestial navigation. 

This sort of "back to basics" approach echoes a growing refrain - our reliance on GPS has made many of our basic skills all but vanish. It's both amazing and a little scary just how reliant we've become on Google Maps, GPS, calculators, computers and other aids to navigate daily life.


Just 100 Years Ago

3/31/16     By Keith Harrod

100 years ago most astronomers thought the Milky Way comprised the entirety of our universe.

 In December of 1912, Vesto Slipher recorded a spectrogram of the Andromeda Nebula that showed a shift of the spectral lines, an indication the Andromeda Nebula was moving towards us at a great velocity – 300 kilometers per second – a result 10 times greater than Slipher expected given the average speed of a star in our Milky Way.

Astronomers of today, using much more capable equipment, measure a blue shift speed for Andromeda of 301 kilometers per second –than 1/3 of 1% difference. Thirty-seven year old Vesto Slipher did a very good job.

 In 1901 Vesto Slipher was a recent graduate of astronomy at Indiana University. Slipher was hired to operate a new, custom built spectrograph for use with the 24” Clarke refracting telescope at the Lowell Observatory in Flagstaff, AZ. Slipher had never operated a spectrograph as large and complex as the spectrograph the Lowell Observatory had built. Nor had Slipher operated a telescope larger than a 4.5 inch refractor. Just a year later Vesto was operating the spectrograph and 24’ telescope with ease. Over time Slipher substantially improved the performance of the spectrograph to boot.

 Slipher wasn’t the first to record the shifted spectral lines of the Andromeda Nebula. Edward Fath had taken a spectrum of Andromeda in 1908 at the Lick Observatory that showed the shifted spectral lines. Fath wrote off the unexpected result as a malfunction of his spectrograph. In early 1913 Slipher sent a print of his Andromeda spectrum to Fath to get an independent check that the shift was real. Slipher held off any grand statement until he had more confirmation and published a brief account of the shifted spectral lines in the Lowell Observatory Bulletin.

 In August of 1914 Vesto Slipher and 65 other US astronomers congregated for the annual meeting of the American Astronomical Society held that year at Northwestern University in Evanston, Illinois. During the same meetings an astronomy graduate student at the Yerkes Observatory named Edwin Hubble was elected for membership in the American Astronomical Society.

 Slipher’s paper “Spectrographic Observations of Nebula” was one of 48 papers read at the meeting. By the summer of 1914 Slipher had recorded the spectra of 14 spiral nebula and was able to show that while some spiral nebula, like the Andromeda Nebula, were moving towards us (blueshift), more spiral nebula were moving away from us (redshift). At the start of his talk Slipher explained he took the Andromeda spectrum just to obtain a spiral nebula’s spectrum. Andromeda is the brightest spiral nebula and thus was the best candidate for having its spectrum recorded. It was only after seeing the extraordinary velocity of the Andromeda nebula that caused Slipher to give attention to the velocity of spiral nebula that spectrum could provide.

 When Vesto Slipher finished presenting his remarkable paper his fellow astronomers did something never before seen at an astronomical meeting – they rose to their feet and gave him a standing ovation.

 Edwin Hubble is commonly, but incorrectly credited with discovering the spectral shift of galaxies caused by their movement towards us or away from us. These spiral galaxy velocity measurements and their significance were understood to be a Doppler shift by several astronomers before 1917.  That short list would include James Edward Keeler (Lick & Allegheny Observatories), Vesto Melvin Slipher (Lowell Observatory), and William Wallace Campbell (Lick Observatory).

 What was still missing was a way to measure how far away the spiral nebula were.

 Edwin Hubble is part of that story thanks to Henrietta Leavitt’s discovery that Cepheid Variable stars could be used as ‘standard candles’ to determine distances. Using the 100 inch Hooker telescope on Mount Wilson Hubble was able to detect Cepheid variable stars in the Andromeda Galaxy in photographs of Andromeda he and Milton Humason made from 1922 to 1923. Hubble used those Cepheid variables to prove the Andromeda Nebula was as vastly far from us, as many astronomers had speculated for years.

 Hubble, then thirty five, was careful to check his results before publishing because his biggest fear was publishing information that could later be shown to be in error. His findings were first published in The New York Times on November 23, 1924, and then more formally presented in the form of a paper at the January 1, 1925 meeting of the American Astronomical Society.

 In 1929 Hubble and Humason studied the relation between distance and the redshift of galaxies and saw that the greater the redshift of a galaxy the further away a galaxy was. The reason for the redshift/distance relationship remained unclear to Hubble, Humason, and most other astronomers.

 Georges Lemaître, a Belgian Catholic priest and physicist, found that Hubble's observations supported the model of an expanding universe based on Einstein's equations for General Relativity. This showed the greater the distance between any two galaxies the greater their relative speed of separation. The speed and nature of the separation velocities indicate the universe is expanding. Of course, we now call the expansion of the universe the Big Bang.



Soon - Jupiter Is Going To Back Up
March 22, 2106      By Keith Harrod

In tonight's sky Jupiter is still moving gradually westward against the background stars.

On April 30/May 1 Jupiter will stop moving west against the stars and on May 3 will start to slowly start moving eastward against the stars - displaying what is known as outer planet apparent retrograde motion.

The graphic in the column on the left illustrates how outer planet apparent retrograde motion is caused when Earth catches up to and overtakes one of the planets further from the Sun than Earth.

This is a type of astronomical observing that can be done with the naked eye and ancient people did just that. Those ancient people watched in their dark, free from light pollution skies as the reddish Mars, bright Jupiter, and twinkling Saturn moved to and fro against the background stars.

To the ancient people they were 'wandering stars' or 'wanderers', from which today's word "planet" was derived.

The Babylonians were the first civilization known to have a functional theory of the planets. The Babylonians lived in Mesopotamia in the first and second millennia BC. The Babylonian Venus tablet of Ammisaduqahe is the oldest known surviving planetary astronomical text. The text on the tablet is a 7th-century BC copy of a list of observations of the motions of the planet Venus that probably dates as early as the second millennium BC.

​The Babylonian 'zodiac' was based on Jupiter's nearly 12 year (11.86 earth yrs) orbit. 

By mid-July Jupiter will set in the west soon after the Sun sets.

Jupiter won't re-appear in the eastern night sky until early March next year - 2017. By then Earth will be far enough ahead of Jupiter that Jupiter will just be re-starting it's westward march against the background stars.

A reminder - planets further from the Sun than Earth orbit at a slower speed and travel a greater distance to orbit the Sun once. Mars takes about 2 Earth years to orbit the Sun once, and Jupiter takes 11.86 earth years to orbit the Sun once.


We Keep Going Back To Mars

March 16, 2106      By Keith Harrod

We first sent spacecraft to Mars as part of the Mariner series of robotic interplanetary probe spacecraft.

Mariner 4 was the first spacecraft to successfully fly-by Mars (July 14 and July 15, 1965) and captured the first images of another planet ever returned from deep space.

Mariner 4 also performed field and particle measurements in interplanetary space in the vicinity of Mars and provided experience in and knowledge of the engineering capabilities for interplanetary flights of long duration.

On December 21, 1967 communications with Mariner 4 were terminated.

Mariners 6, 7, and 9 also visited Mars. Mariners 3 & 8 were lost due to launch failures.

Since then we have sent many more spacecraft, orbiters and landers, to the Red Planet because Mars is the closest planet we can search for life on.

The latest mission, the ExoMars 2016 orbiter and lander was launched 2 days ago from the Baikonur Cosmodrome, Kazakhstan on a Russian Proton rocket. ExoMars 2106, an astrobiology project, is scheduled to arrive at Mars on October 19, 2016.

ExoMars 2018 is slated to land a rover on Mars.

Note: Favorable launch windows for mars occur every 2 years.

Additional reading:


•  http://www.space.com/32274-why-we-keep-going-to-mars-exomars-2016.html

• http://exploration.esa.int/mars/46048-programme-overview/

• https://en.wikipedia.org/wiki/ExoMars_Programm



Scientists To Drill Into Dinosaur Killer Asteroid Impact Crater
March 7, 2016       By Keith Harrod

Walter Alvares is most widely known for the theory that dinosaurs were killed by an asteroid impact just off the tip of the Yucatan peninsula in the Gulf of Mexico - the Chicxulub impact crater. Walter developed the theory in collaboration with his father, Nobel Prize winning physicist Luis Alvarez.

Frank Asaro and Helen Michel helped confirm that a thin clay layer occurring right at the Cretaceous-Tertiary (K-T) boundary in rock strata around the world was highly enriched in the element Iridium by using the high-precision technique of neutron activation analysis they had developed at the Lawrence Berkeley National Laboratory.

Since Iridium enrichment is common in asteroids, but very uncommon on the Earth, Walter & Luis Alvares postulated that the thin layer had been created by the impact of a large asteroid with the Earth and that this impact event was the likely cause of the Cretaceous–Paleogene extinction event that not only caused the extinction of the dinosaurs but some three-quarters of all plant and animal species on Earth.

Starting April 1, 2016, scientist will drill into the Chicxulub impact crater, formed 65.5 million years ago, to study how life recovered following the mass extinction at the end of the Cretaceous period.

Researchers hope to locate signs in the crater that will verify existing impact models, and show whether or not the crater was a prime breeding ground for microbes that helped return life to the region. Should the drilling yield the hoped for evidence, it will help fill a gap in Earth's history and illustrate just how persistent life can be despite seemingly insurmountable odds.


Hubble Space Telescope Site - News Release

March 3, 2016

NASA's Hubble Space Telescope is an amazing time machine; by looking back through space, astronomers actually look back through time. Now, by pushing Hubble to its limits, an international team of astronomers has shattered the cosmic distance record by viewing the farthest galaxy ever seen. Named GN-z11, this surprisingly bright, infant galaxy is seen as it was 13.4 billion years in the past. The astronomers saw it as it existed just 400 million years after the big bang, when the universe was only three percent of its current age. At a spectroscopically confirmed redshift of 11.1, the galaxy is even farther away than originally thought. It existed only 200 million to 300 million years after the time when scientists believe the very first stars started to form. At a billion solar masses, it is producing stars surprisingly quickly for such an early time. This new record will most likely stand until the launch of Hubble's successor, the James Webb Space Telescope, which will look even deeper into the universe for early galaxies.

See the rest:
The Full Story
See All the Images

Video showing where in the sky GN-z11 is


2016 Jupiter Opposition

March 1, 2016      By Keith Harrod

On March 8, 2016 at 5:00 PM CST (11:00 UT - Universal Time) Jupiter will be as close to Earth as it will get this year.

When Jupiter is at opposition it's apparent diameter from Earth is 50 arc seconds. Jupiter's apparent magnitude for this years opposition will be -2.5. That's 1 full magnitude brighter than Sirius, the brightest star in the sky with an apparent magnitude of -1.46.

Jupiter will be high in the sky this month when it crosses the meridian each night about midnight putting Jupiter in a good viewing location above the horizon from about 10 pm to 2 am.

For more information visit: http://www.universetoday.com/127542/jupiter-our-guide-to-opposition-2016


Exploring the Southern Sky​ - ESO at 50
February 23, 2016     By Keith Harrod
Six video episodes by the European Space Organization.


Video - Extremely Close Meteor Fall

February 16, 2016     By Keith Harrod

The latitude and longitude shown in the video indicate the location is Melbourne, Australia overlooking Port Phillip. Loud sonic boom.



Video - One Year of the Sun in 2.5 Minutes

February 16, 2016      By Keith Harrod

Shown with light at a wavelength of 171 angstroms from Jan. 1, 2015, to Jan. 28, 2016.​

​See at: http://www.space.com/31942-suns-busy-buzzy-life-1-year-in-2-5-minutes-4k-video.html


​​Gravity Waves Detected

February 11, 2016     By Keith Harrod

The Laser Interferometer Gravitational-Wave Observatory (LIGO) is a large-scale physics experiment and observatory to detect gravitational waves.

Initial LIGO operations between 2002 and 2010 did not detect any gravitational waves.​

LIGO was shut down for several years so more sensitive detectors could be installed.

By February 2015 two advanced detectors had been installed and could be used in an engineering mode that allowed the first formal science observations using the advanced detectors at about four times the sensitivity of the initial LIGO interferometers.

On February 11, 2016, 1012 authors of the LIGO Scientific Collaboration and Virgo Collaboration published a paper about the detection of gravitational waves, from a signal detected at 09.51 UTC on 14 September 2015 of two ~30 solar mass black holes merging together about 1.3 billion light-years from Earth.



Solar Magnetism
February 8, 2016     By Keith Harrod     
Our Sun has a complex magnetic field.
The Sun's magnetic field extends out to all of the solar system's planets.
NASA has combined computer modeling and solar imagery to make a video they shared online January 29.

See more at: http://www.space.com/31864-magnetic-sun-video.html

More regarding possible Planet Nine on Space.com
February 4, 2016     By Keith Harrod
". . . Batygin and Brown didn't see Planet Nine; rather, they inferred its existence based on the odd orbital characteristics of six bodies in the "scattered disk" portion of the Kuiper Belt . . .

See more at: http://www.space.com/31817-planet-nine-existence-question.html#sthash.Gqc0Zyxr.dpuf​​

China's Moon Lander & Rover Photos
January 29, 2016     By Keith Harrod
Planetary Society blogger Emily Lakdawalla took the time to explore the recently released to the public China Chang'e Lander and Yutu Rover Rover made photographs.

Here is the link to Emily Lakdawalla's The Planetary Society blog.



January Club Meeting

By Keith Harrod     
As usual, the January club meeting was occasion for the "New Year Pot Luck Dinner" & meeting.
The food choices offered us all a cornicopia of plenty.
We had Sloppy Joes & buns, fresh raw veggies and dip, green bean casserole, potato chips, cole slaw, spaghetti, brownies, chocolate cake, and more.

Meeting and public event dates were chosen for the new year and we elected 2016 club officers.
• Jim Bonser was re-elected President.
• Keith Harrod was elected Vice-President
• Gail Schertz was re-elected Secretary/Treasurer

Possible New Planet For Our Solar System
January 20,  2016     By Keith Harrod
CalTech researchers Mike Brown and  Konstantin Batygin announced they believe a number of features detected beyond the orbit of Neptune in the Kuiper Belt, home of lots of small icy objects and various debris, indicate there may be a planet with a size of about 10 Earths orbiting about 20 times further out than Neptune's orbit.

The irony that Mike Brown was instrumental in causing Pluto to lose it's 'planet' status has not been lost on the astronomical community.

The suspected new planet would be so far from the Sun that it would receive, and reflect, very little sunlight making it difficult to detect with our current astronomical instruments. 

Time will tell if there is, or isn't, a 10 earth mass planet out there 20 times further from the Sun than Neptune.



Resources & Links


The Astronomical League

Sky and Telescope.com


Sun - Rise & Set times

Moon - Rise & Set times


For locating dark sites for

visual observing

Light Pollution Map

For locating dark sites for


Jupiter Galilean Moons & Shadows

Messier Objects - By Constellation

Solar System Scope.com

A solar system orrey

Cloudy Nights - Astronomy Forums

Stellarium- A free open source planetarium for your computer

Virtual Moon Atlas - A free Moon atlas for your computer

Where is M13?

A free application that shows the relative position of deep sky objects in the night sky to our galaxy.

​​Astronomy News



 Amateur Astronomers

       of Central Iowa

Outer Planet

Retrograde Motion

As Earth (blue) passes a superior planet, such as Mars (red), the superior planet will temporarily appear to reverse its motion across the sky.