Last June, a Web user happened to notice an artifact in Google Sky, a site that features several different star atlases you can drill down into to see closeups of nebulas, galaxies and stars. It’s a great tool even with its occasional foibles which we’ll explore in just a moment. Anyway, this guy claimed he found a new, green-glowing “asteroid” which no one else had seen before and posted it on Youtube complete with an ominous soundtrack. Claims later appeared that it was moving toward the Earth. As you’re no doubt aware, Youtube is nearly as good at disseminating nonsense as it is useful, funny and educational content.
A quick look at the “asteroid” will tell you right off it couldn’t possibly be a real object. First, asteroids move. During a time exposure, the green blob would have appeared as a line (or a series of repeated images depending on how the picture was taken), not a sharply-defined object. Even if by some exceedingly rare chance it was headed directly toward Earth and not off to one side or another, its edges would appear soft in the many minutes it took to expose the image.
Second, it’s too big to have been missed. Professional automated surveys as well as an army of amateur astronomers equipped to the teeth with big scopes and high-end electronic cameras would have picked up such a large object. You can measure the object’s apparent size by comparing its length to the known distance between stars on the atlas. I measured conservatively and came up with 30 arc seconds or 1/60th the diameter of the full moon.
The dwarf planet Ceres, located in the asteroid belt, is 590 miles in diameter and measures about one arc second across. The green “asteroid” would be 30 times larger or 17,700 miles. That’s more than twice the size of Earth. Naaah … I don’t think we’d miss that one.
Of course, I’m assuming it’s located in the asteroid belt between Mars and Jupiter. If it’s farther, it’s even bigger. But if it’s much closer, it could look bigger but in reality be much smaller. Ah, but there’s the rub again. If it’s closer, it would appear to move faster and make an even more obvious trail during a time exposure.
Finally, you can go back to check the original source catalog. When you do, you’ll discover there’s nothing at all at the scary green asteroid’s position. As for it moving toward the Earth, even if it was real, you’d need more than one image of it to know in what direction it was moving.
So what is it? Probably a piece of fuzz or maybe a defect in the photographic plate used to take the picture or some sort of glitch that popped up when Google Sky was stitched together by digitizing and compiling photos from original catalog sources like the Sloan Digital Sky Survey and Digital Sky Survey Consortium.
Just for fun, I poked about Google Sky to see what else I could dig up that looked menacing and was delighted to stumble across a wonderful assortment of oddities, a literal zoo of weird flares, scratches, fuzz, blobs, overexposures and more that at first glance might be used by the overzealous to announce a new planet, UFO or world-ending asteroid. Sharpness was a dead giveaway in most of the artifacts. A real, extraterrestrial object would trail or show multiple images during a time exposure.
And that’s my point. Before jumping to conclusions and tossing out over-the-top “theories” about some oddity in a photo, it’s important to consider logical alternatives, gather background information and if necessary, go back to the original source. Google Sky has known problems with missing chunks of data during the digitizing process, over and underexposed pictures, flares and lots more, but for all its flaws, it’s fun and useful. Now on with the show!
I only spent about a half hour looking for artifacts. There are many more. If you do see something in Google Sky that makes you wonder, you can check it out by using the Aladin previewer, which uses maps from the original sources without the errors introduced through stitching. Type in the object’s coordinates – called right ascension (R.A.) and declination (Dec.) – in the target box and press Go. For instance, the coordinates of the featured asteroid glitch are R.A. 5 11 33.7, Dec. -12 50 30. You can also use the Simbad Astronomical Database to search a whole variety of original catalogs and atlases. More information on Google Sky glitches can be found HERE.