Quarter-Mile Asteroid Gets Checked by Radar  

The entire universe in blog form
June 26 2014 7:30 AM

Near-Earth Asteroid Gets Checked by Radar

asteroid 2014 HQ124
Mosaic of radar images of the near-Earth asteroid 2014 HQ124, which passed the Earth earlier this month. It rotates in less than 24 hours, as can be seen by the apparent motion here.

Photo by NASA/JPL-Caltech/Arecibo Observatory/USRA/NSF

2014 HQ124 is an asteroid that was discovered in April 2014 and was quickly determined to be a near-Earth asteroid, one whose orbit brings it pretty close to our fair world.

Phil Plait Phil Plait

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!  

On June 8, it passed a mere 1.4 million kilometers (900,000 miles) from us. That’s pretty far in human terms—more than three times farther away than the Moon—but on a cosmic scale that’s a close shave. Even that close, a typical asteroid is still too far to resolve (that is, see it as more than just a dot) with optical telescopes … but not to radio telescopes.

Advertisement

Combining the power of the Goldstone 70 meter dish with the Arecibo 300 meter ‘scope, astronomers pinged HQ124 with pulses of radar, creating some of the highest-resolution images of a near-Earth rock ever obtained. They combined them into a pretty nifty animation, too:

Mind you, what you’re seeing there is not an image in the way we normally think of them. The radar pulses are sent to the asteroid, where they bounce off the surface and are reflected back to Earth. By timing the pulses and measuring their wavelength very carefully, the shape and rotation rate of the asteroid can be determined. I have a much more detailed explanation in a post about another asteroid undergoing this treatment, and Emily Lakdawalla has the technical info on how this works.

close up of the asteroid
The first frame of the mosaic shows craters and hills on the 400-meter long rock.

Photo by NASA/JPL-Caltech/Arecibo Observatory/USRA/NSF

The observations show HQ124 to be an elongated rock about 400 meters (1,300 feet) across, and about half that in width. Many asteroids have this sort of shape, and it may be because they’ve been battered and sculpted by impacts over the eons, or it may be because it’s what’s called a contact binary; two asteroids that came into contact and stuck together. Quite a few like this are known, and even some comets, too.

You can see that HQ124 isn’t smooth, either. There are craters and hills on it, meaning it’s suffered the slings and arrows of impacts over time. Every asteroid we’ve seen up close is like this; which isn’t terribly surprising. While space is big, and objects few and far between, there are billions of small rocks out there. Given billions of years, well, the odd encounter or thousand is inevitable.

Asteroids are leftover bits from the formation of the solar system. Planets and moons have changed a lot since that time—just the process of growing to be big changes the chemical composition of the material of a planet. Asteroids have changed too, but not nearly as much, and studying them gives us a pretty nice window into what things were like 4.5 billion years ago when the solar system was young. Space probes give us the best view of asteroids, of course, but they’re expensive and we don’t have too many just yet. Radar observations of asteroids that pass us by give us fantastic opportunities to peer at these time capsules, and help us understand the birth and evolution of our cosmic neighborhood.

And because why not:

Radar trap
Speed trap outside of Ottumwa, Iowa.

This picture is a meme all over the Internet, and I couldn't find a source. If you know who originally made it, please let me know! They deserve credit.

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!  

TODAY IN SLATE

Jurisprudence

Don’t Expect Adrian Peterson to Go to Prison

In much of America, beating your children is perfectly legal. 

Ken Burns on Why Teddy Roosevelt Would Never Get Elected in 2014

Cops Briefly Detain Django Unchained Actress Because They Thought She Was a Prostitute

Minimalist Cocktail Posters Make Mixing Drinks a Cinch

How the Apple Watch Will Annoy Us

A glowing screen attached to someone else’s wrist is shinier than all but the blingiest of jewels.

Books

Rainbow Parties and Sex Bracelets

Where teenage sex rumors come from—and why they’re bad for parents and kids.

Books

You Had to Be There

What we can learn from things that used to be funny.

Legendary Critic Greil Marcus Measures and Maps Rock History Through 10 Unlikely Songs

Catfish Creator Nev Schulman’s Book Is Just Like Him: Self-Deluded and Completely Infectious

Behold
Sept. 12 2014 5:54 PM An Up-Close Look at the U.S.–Mexico Border
  News & Politics
Jurisprudence
Sept. 14 2014 2:37 PM When Abuse Is Not Abuse Don’t expect Adrian Peterson to go to prison. In much of America, beating your kids is perfectly legal. 
  Business
Moneybox
Sept. 12 2014 5:54 PM Olive Garden Has Been Committing a Culinary Crime Against Humanity
  Life
Inside Higher Ed
Sept. 13 2014 8:38 AM “You’re More Than Just a Number” Goucher College goes transcript-free in admissions.
  Double X
The XX Factor
Sept. 12 2014 4:05 PM Life as an NFL Wife: “He's the Star. Keep Him Happy.”
  Slate Plus
Behind the Scenes
Sept. 12 2014 5:55 PM “Do You Know What Porn Is?” Conversations with Dahlia Lithwick’s 11-year-old son.
  Arts
Brow Beat
Sept. 14 2014 7:10 PM Watch Michael Winslow Perform Every Part of “Whole Lotta Love” With Just His Voice
  Technology
Future Tense
Sept. 12 2014 3:53 PM We Need to Pass Legislation on Artificial Intelligence Early and Often
  Health & Science
New Scientist
Sept. 14 2014 8:38 AM Scientific Misconduct Should Be a Crime It’s as bad as fraud or theft, only potentially more dangerous.
  Sports
Sports Nut
Sept. 12 2014 4:36 PM “There’s No Tolerance for That” Pete Carroll and Jim Harbaugh say they don’t abide domestic abuse. So why do the Seahawks and 49ers have a combined six players accused of violence against women?