Observing Planets

Mercury is always so low on the horizon, that it is difficult for me to make any worthwhile observations. The last time I observed Mercury it was moving across the face of the sun, which is called a Transit. Mercury is near the bottom of the image - the other dark, irregular object, is a sunspot.

I've seen one transit of Venus (June 8, 2004) , and hope to see one more in my lifetime in 2012. If you miss that one, you have to wait until 2117 for the next one.

Although the transit of Venus is rare, seeing Venus is easy. It is often the brightest star-like object in the morning or evening skies. Through the telescope, it appears, as does Mercury, as a moon-like phase.

Sometimes, Venus is just a downright disappointing blob.

At other times, it is a spectacular phase.

I've made an animated GIF from 18 images I've been taking during 2004, 2005, 2006 and 2007 of the planet Venus. You can tell how the distance between Venus and the Earth increases and diminishes over time, and how the planet Venus, being an Inner Planet (between us and the Sun), has phases like the moon.

The images were taken through the telescope at http://www.slooh.com/.

To see the animation, click http://www.myslooh.com/data/members/1627/1198986501.gif.


Mars is often a very disappointing object for the inexperienced astronomer - and when it is a great distance away, it can be disappointing to anyone.

However, as Mars moves to "opposition," meaning it is opposite from the sun, which actually simply means it is pretty close to us, we can make out some features of Mars.

Jupiter is always fun to watch. The four brightest moons, called the Galilean Moons because Galileo discovered them, move quickly around the planet. Their movement is easy to discern in hours rather than days. There 11 moons known to orbit Jupiter when I was a child. We now know of 63 - well, at least that is what the figure was last week.

The Red Spot, seen peaking over on the left side, is a good target to look for among the Jovian clouds.
Of course, nothing beats seeing the planet's atmosphere scarred from having been hit by a comet.


Saturn has a similar cloud structure, but it is the rings that capture our attention.

Twice every 29.2 years, the rings of Saturn appear edge on. In 2002, the rings were as open as they get in the current cycle. I missed it by a couple of years, making my first photo in 2004.

They will be edge on in 2009, and as you can see the rings are beginning to appear smaller than in 2004.

Uranus appears featureless through small telescopes. The challenge is to try to identify the moons.

Between these two images of Uranus, I imaged the 5 moons of Uranus known to exist when I began to become interested in astronomy as a child. We now know of 27 moons orbiting Uranus.
The most interesting thing about observing Neptune, besides watching it move against the background stars from night to night, is to observe its moon, Triton. When I became interested in astronomy as a child, there were only 2 known moons of Neptune. There are now 13 known moons. Triton is the largest and was discovered just 17 days after the discovery of Neptune. You can see why - the moon is bright even at this 200x magnification.

Pluto offers nothing of interest to even the largest earth-bound telescopes. It is not difficult to see, however. The challenge is to know what you are looking at. Pluto just appears as a dim star. The best thing to do is to image the planet over several nights and to determine which star-like object is changing position in relation to the other stars.

No comments: