The moon is our nearest celestial neighbor. Look out the window, day or night, and about 75% of the time, you can see the moon. Maybe a little less where Astropotamus lives – My city ranks in the top 25 for “most cloud cover” of all cities in the US with more than 50,000 people. But I digress.
The moon is about 250,000 miles away. So light takes about 1.3 seconds to travel from the moon to the Earth. Looking at the moon isn’t traveling too far back in time, but it’s still fun anyway. The moon is about 1.2% of the mass of the Earth and about 2.0% of its volume. That means the moon is less dense than the Earth – about 60% of the Earth’s density of 5515 kg/m³. If you weigh 100 kg (220 pounds) on the Earth, you would only weigh 16.5 kg (36.3 pounds) on the moon. Instant weight loss – just add rocket!
Because the moon rotates once for every rotation about the Earth (every 29.5 days or so), we always see the same side of the moon. It does wobble a bit, so we can sometimes glimpse what’s just beyond the edge, but we never really see the dark side of the moon. But the moon does rotate around the Sun as well as the Earth. So even though we always see the same side, the Sun sees every side. So bring a parka and your swim suit because it’s about -240F on the dark side and about 225F on the light side.
Moon facts are fun, and Astropotamus loves the moon – it’s the easiest thing to see in the sky besides our Sun. So I was quite pleased to come home on 07-Apr-2011 and find a nice not-quite-quarter moon growing in the low western sky. I hooked up the Time Machine and got the camera out and did some focal plane imaging. You can see some of the shots I got at the end of this post.
When the moon started to dip below the tree line and go behind some very high sirrus clouds, it was time to switch targets. So I took the camera off the T adapter and put it on the piggyback mount which lets the camera sit on top of the Time Machine. This let me use a wider angle lens to take in about 15 degrees of the sky at once. Good enough for some very nice images of….well, I guess you’ll just have to come back tomorrow to see what I found. Of course, I’m writing this on 08-Mar-2011, and tomorrow for you is 11-Apr-2011, so by the time you see tomorrow’s pictures, it will be three days ago.
My, time travel can be complex sometimes!