Ever seen the Moon move?

I have been spending a lot of time at the office over the last couple of weeks (you know, beginning of a new semester and all) and happened to notice something interesting going on in the sky. 
On Friday 16 Sept, at around midnight, I went outside and noticed the bright waning moon was very close to Jupiter.  I thought it was cool, and I wish I had a good camera to take a picture.  Since all I had was my phone on me I dug it out, equipped with a 5 MP camera (not bad), to see if I could pick out the bright pair.  I snapped the below pic:

The moon is the bright circle left of centre, and right of centre there is a TINY white dot.  That’s Jupiter.  I immediately posted the pic to twitter (@jesserogerson) to share with the world.

If you want to go see Jupiter with your own eyes, go look off to the East around 10:30pm, it will be a very bright star.  As the night goes on, it’ll rise high up still a bit to the South, and then set in the west early in the morning.  Jupiter is BY FAR the brightest star out, in fact the only thing brighter would be the moon.

Anyway I was pretty happy with that, I was surprised that my camera could pick up both objects.  Very happy!  Then the next night (Sat 17 Sept) I happened to be out again at around midnight and saw the same pair in the sky…only this time they looked a little different.  I snapped the below pic and posted to twitter:

Pic is taken with the same magnification/zoom, same camera, same everything.  Though now you will notice the moon has approximately doubled its distance from Jupiter.  This change is due to the motion of the moon around the Earth.

The Moon has an orbital period of approximately 27.3 days.  In that time it travels approximately 2.4 million km.  Happily, I happened to be out sunday evening (18 Sept) around midnight and so snapped one final image to show you.

The Moon had moved further along its orbit and created more distance between it and Jupiter.  The orbit is roughly a circle, though, so I suspect in about 25 days the Moon will be right beside Jupiter again.

The reason I think this is so cool is because I took me a grand total of 2 minutes to do (30 seconds per image, give or take), I did it with a crappy handheld camera-phone, and I did it from the middle of the city.  With little-to-no-effort or equipment I was able to show the motion of our Moon using a fixed object in space.*

You do not have to be some fancy astronomer to figure out what is going on up there!  You just have to be interested, people!


* I should note that Jupiter IS NOT fixed in space.  Jupiter moves around the Sun just like us.  Based on the relative position of the Earth/Jupiter/Sun system, Jupiter will be moving in the sky.  In fact the word ‘planet’ is derived from the latin word for ‘wandering star.’  However, Jupiter’s orbital period is 11.9 years, Earth’s is 1 year.  The change in the position of Jupiter against the background stars is too small to be noticeable over a three day period.

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