🔭 Updates an earlier post to include recent changes and new information.
As an amateur astronomer, I use desktop planetarium software to plan viewing sessions and keep track of the planets and Moon. There are many products available for all computer platforms and smartphones. A Google search yields links to many sources. I downloaded and use the open source Stellarium on my desktop computer. It can be customized to your location and is free. For Android and Mac phones and tablets, I like SkySafari. It isn’t free but is inexpensive.
Online planetarium sites are popular and offer many features. Below are highlights of some I find interesting. Each has multiple features, a unique look and feel, and different levels of detail. They can help satisfy your curiosity about astronomical events.
I have included only a few select sites and links since so many are available. I welcome reader questions or reviews about using these tools or others you find helpful.
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Launched 15 October 1997, the Cassini Mission is in its 20th year. It reached Saturn and entered orbit on 1 July 2004. Details of the mission can be read at this Wikipedia summary. This post is mostly about the maneuvers by Cassini to change its orbit and make 22 close encounters with Saturn in what is called the Grand Finale. End of mission is scheduled for 15 Sep 2017 when the spacecraft plunges into the atmosphere of Saturn ending a long and brilliant exploration of the famous ringed planet, its rings, and 62 moons.
Clean Room Workers Ready Spacecraft | NASA | 1996
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Venus is closer to the Sun and orbits faster than Earth. Earth takes just over 365 days. Venus orbits in just under 225 Earth days. During the recent few months, Venus was bright and easily visible in the evening sky as it caught up to and passed Earth. In doing so, it came closer and appeared larger when viewed with a telescope or binoculars. This animation from a desktop program illustrates their motions. Mercury is not shown in order to simplify the view. The sizes are exaggerated.
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How I saw Venus last evening. Only about one week until inferior conjunction. After that, Venus appears in the morning sky as a thin crescent.
100 ISO | 1/250 sec
A prism of high quality glass sits in a south window above our mantle. It is part of a surplus optical instrument from WW-II. The window crank gives a sense of its 2″x1″x1″ size.
When the Sun is low in the sky during late fall and winter, light through the prism casts a large full spectrum on the wall on the opposite side of the house. This is a closeup of the spectrum. It is always a delight to see the colors move slowly across the wall during the middle part of a sunny day.
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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.
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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.
NASA posted this short video to explain what to watch for and when. May your skies be fair.