How to Detect Killer Asteroids

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How to Detect Killer Asteroids
Photos: Earth Science and Remote Sensing Unit, NASA Johnson Space Center, and Juliann Brown

It’s inevitable — life on Earth will be incinerated by a catastrophic asteroid strike. Unless we see the asteroids coming first.

Scientists discover about 1,000 near-Earth objects (NEOs) every year, but that’s not nearly fast enough. There are millions out there. A powerful new orbiting telescope called Sentinel is scheduled to launch by 2019. Until then, we’re flying nearly blind.

I spent a fascinating summer night at the 36″ reflector telescope “Nellie” at Chabot Space and Science Center in Oakland, California, with Gerald McKeegan of the East Bay Astronomical Society as my guide. He showed me that asteroid-spotting is no cake walk, but it’s totally doable. Here are four ways you can help right now.

Discovery by telescope

Point a really nice telescope overhead, and set your mount control to track the star field. With a 10″ aperture, you’ll be able to detect objects of magnitude 19, or even 20–21.


Take 5 or 10 images with your digital camera, wait a few minutes, then take another set. Even if there’s an asteroid there, you won’t see it. Most NEOs are just too dark. To provide enough magnitude, you’ve got to “stack” 5 or more photos in image processing software. Astrometrica is specifically designed for asteroid spotting; it uses the FITS image format (like a TIFF with an astronomy metadata header), so first convert your images using one of these programs.

Now look for a tiny dot that moves! If you find one, Astrometrica will automatically email a report to NASA’s Minor Planet Center (MPC), operated by the International Astronomical Union. Maybe you’re looking at a known asteroid or space junk — or maybe you just discovered a new NEO.

Discovery online


Don’t have a great telescope? Surf to Asteroid Zoo, a joint effort of NASA and the asteroid mining company Planetary Resources. On this website, anyone can flip through thousands of existing sky survey photos, and look for, yep, a dot that moves. Spot one, mark it, and you might just be the discoverer of an asteroid previously unknown to science!

Orbit confirmation

In truth, little is known about a lot of “known” NEOs. Scientists need more data to confirm orbits and speeds, and you can provide it. Point your scope at a known NEO; you can check out this list of targets. Then analyze your photos in Astrometrica and submit your report to the MPC. McKeegan and I tracked asteroid K14M05P (aka 2014 MP5), first discovered in June 2014 — and confirmed it’s in a hazardous orbit near Earth.

Asteroid characterization


If you’re going to deflect a deadly space rock with superlasers or send Bruce Willis to nuke it, you’ll need to know how big it is and how it’s spinning. By analyzing an asteroid’s “light curve” — fluctuations in brightness over time — you can figure its rotation period, and even estimate its size, mass, and shape. Follow the MPC’s Guide to Minor Planet Photometry; you can use Astrometrica or try more powerful software such as MaxIm-DL or MPO Canopus. Then submit your light curves to the MPC’s Collaborative Asteroid Lightcurve Link (CALL) website and you might just save your favorite planet.


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