I don't get nearly enough chances to use Celestia in my classroom. I've loved messing around with Celestia for years, but it's the rare student who shares my enthusiasm for astronomy. In class I will use Celestia to demonstrate gravitational orbits - moons around planets, planets and comets around suns, stars orbiting stars orbiting more stars.
During one such class this past year, one of my brightest students asked me if I had heard about the time an asteroid had circled Earth three or four times and then disappeared. I encouraged her to explain further, though I was skeptical. So she whipped out her smartphone, found an animation of the event, and showed it to me. Sure enough, there it was.
The animation had specific dates, and the asteroid had a designation that I recognized as legit; J002E3. I promised the class that I would gather more information for the next class.
Wikipedia has an entry about J002E3, and in that page I found the NASA/JPL animation my student had shown me. I also found an amazing story. J002E3 was indeed first thought to be an asteroid, but later determined to be space junk, namely the third stage of the Apollo 12 Saturn V rocket launched in 1969. The rocket stage was intended to wind up in orbit around the Sun, but it didn't quite make it, and is now technically still in orbit around Earth. It's in a semi-stable orbit, though - J002E3 spends decades circling the Sun before it re-enters the Earth-Moon system, circles the Earth a half-dozen times, and gets shot back out around the Sun. Eventually it will crash into either the Earth or the Moon.
J002E3 orbited the Earth six times from the spring of 2002 until late spring of 2003, and this is what the animation shows. I presented the animation to my students on the SmartBoard, and I knew right away that I would have to change it. The file is an animated GIF, which cannot be paused, have its speed changed, or be run in reverse. The deep blue orbital path, which shows up nicely on a computer screen, did not project brightly enough on the SmartBoard to be seen easily. The GIF's dimensions were too small. I would have to do a little editing and then turn it into a video.
Photoshop is the perfect tool for this. It will read all the frames of an animated GIF and turn them into individual layers. You can edit the layers, and then turn them back into a GIF or a video. I first changed the dimensions, doubling both the width and height. Then I changed the color of the orbit in each of the frames. This took some painstaking effort - about 80% of the work could be done very quickly, but each of the 516 frames had to be carefully checked. I exported it as an MP4 video which I posted on YouTube.
NASA link: https://cneos.jpl.nasa.gov/news/news134.html
Animation versions & credit: https://cneos.jpl.nasa.gov/doc/j002e3/
No comments:
Post a Comment