Saturn | Rings and Moonlets

Saturn is one of the favorite objects of astronomers. It has been viewed and imaged millions of times. The Cassini-Huygens spacecraft orbits Saturn and returns images of the rings, moons, and moonlets. Operated at Saturn since July 2004, Cassini yields views of the fine structure details of the rings.

Galileo thought there were three objects when he telescopically viewed Saturn in March 1610 noted in a letter to his patron Medici in July 1610. From The Galileo Project at Rice University:

I discovered another very strange wonder, which I should like to make known to their Highnesses . . . , keeping it secret, however, until the time when my work is published . . . . the star of Saturn is not a single star, but is a composite of three, which almost touch each other, never change or move relative to each other, and are arranged in a row along the zodiac, the middle one being three times larger than the lateral ones, and they are situated in this form: oOo.


U of IA Robotic Telescope | Winer Observatory | Sonoita AZ


Show me more…

Lunar Eclipse | Images | Tetrad Part 4

We left central Illinois well before sunset. It was overcast. The prospects for seeing the lunar eclipse were not very good. As we headed northwest toward our home in eastern Iowa, the skies showed signs of improvement. Minutes before the Sun set, it shined brightly through a big opening in the clouds. That was a good sign.

Driving west on I-80, we could see brightness in the east behind the few remaining clouds indicating that the full Moon had risen. We stopped for a driver change. There was the Moon just entering the shadow of the Earth. I periodically rotated the rearview mirror up to take a peek at the eclipsing Moon behind us. Eclipse in progress.

After we unpacked the car, I put my camera on a tripod on the front porch. This first shot showed the Moon about 50% into the umbra. Notice the curve of the Earth’s shadow. It gives a sense of the relative sizes of the Moon and Earth.


Show me more…

Lunar Eclipse | 27 Sep 2015 | Tetrad Part 4

Previous posts about this tetrad of lunar eclipses can be found by following this link. Visit those links for explanations of the phenomenon if you need them.

Part 4 of this tetrad takes place Sunday evening 27 Sep 2015 for North and South America. First evidence of the partial phase begins at 8:07 pm central daylight time. The total eclipse phase begins about an hour later at 9:11 CDT. Totality lasts a little more than an hour ending at 10:23 CDT.

The timing of this lunar eclipse is very good for viewers in North and South America. It begins when most people are still up. If sky conditions are not overcast, it will put on a show all evening. You do NOT need eye protection.

You don’t have to watch it continuously. Look every 20-30 minutes. You will see the Moon change color and coverage as it transits Earth’s shadow.

8 Oct 2014 | 5:56 am | f/2.8 | ISO 200 | wb daylight | 2 sec | J. Ruebush


This is also a supermoon. It will be about 7% larger than normal because it will be closest to Earth in the slightly non-circular orbit. You will not likely notice it unless you have two photographs to compare such as these.

Regular full moon vs supermoon comparison Source: Karen Roe via

Regular full moon vs supermoon comparison
Source: Karen Roe via


NASA posted this short video to explain what to watch for and when. May your skies be fair.

MESSENGER | Mercury Mission Ends

The MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft is due to crash into the surface of Mercury on April 30, 2015 after it runs out of fuel. Impact will be at a speed of 8,750 miles per hour (3.91 kilometers per second) on the side of the planet facing away from Earth. It first arrived into orbit around Mercury March 17, 2011. The instrument payload has provided a wealth of information. It is the first spacecraft to orbit that planet. It has given us views of Mercury that mankind has never seen. The spacecraft has acquired more than 255,000 images and a vast amount of other data. The entire surface has been mapped.

NASA/Johns Hopkins Univ. | Applied Physics Laboratory | Carnegie Inst. of Washington

Launched August 3, 2004, the accomplishments of MESSENGER are many. This graphic from 2014 celebrates many of those.

Show me more…

Lunar Eclipse | 4 Apr 2015 | Tetrad Part 3

Previous Tetrad Posts:

Tetrad Part 1 Explanation and what to expect

My images of Part 1

Tetrad Part 2 My images of part 2

What To Expect

The third part of the Lunar Eclipse Tetrad takes place just before sunrise on April 4, 2015, low in the western sky for us in the central U.S. For observers in the eastern time zone of the U.S., they will not see the total eclipse phase. The Moon will set before it begins. They will see some of the partial eclipse phase. Those of us in the central time zone will see the total eclipse phase just as the Moon sets in the west. Observers farther to the west will be able to witness more of totality before it sets. The best location is Hawaii except that you need to observe in the middle of the night.

I prepared a video with my desktop planetarium software of the view to the west horizon for my location in Iowa. The time covered is from 5:10 am until a few minutes after 7:00 am. Note that the Moon will set at the same time that the Sun rises. This can only happen during a total lunar eclipse because of their alignment with Earth.

Show me more…

Asteroid Flyby | Did You Miss It?

Asteroid 2004 BL86 traveled by Earth January 26, 2015. It was about 3x farther from Earth than our Moon. There was no danger. It was an interesting event. It happened during the daylight hours for me. It was also clouded over. There was no chance to see it with my own equipment. So, I visited an online broadcast from Europe. The Virtual Telescope Project successfully tracked it.

The event was hosted by Gian Masi, astrophysicist and science communicator. They posted a 28 minute YouTube video. Broken clouds interrupted the view at times. Their telescope tracked the asteroid at the center of the window. A 10 second time exposure captured an image. Each 15 seconds, a new image was scanned over the old one. The asteroid remains centered. The star field moves slightly. I extracted a brief clip from one cloud-free interval if you don’t want to watch the entire video. This object was moving very fast. It traveled the equivalent of 5 Moon diameters each hour.

Fellow blogger, Alex Autin, posted on …Things I Love more exciting information about this asteroid. It has a moon! Visit her site. If you like astronomy, follow her blog. Radar images from the 230-foot-wide NASA Deep Space Network antenna at Goldstone, California, revealed the moon to be about 230 feet wide. The asteroid is about 1100 feet wide. The full video is on her site or here at the NASA JPL YouTube channel.

NASA Deep Space Network