The Washington Post

Is this asteroid flyby too close for comfort?

Nov 08, 2011

Brace yourselves! There's an asteroid racing toward Earth on Nov. 8, missing our planet by only 200,000 miles. According to the National Science Foundation, this flyby will be a great excuse to break out your telescope.

NSF astronomer Thomas Statler will answer your questions about "Asteroid 2005 YU55," from the size and shape to whether or not its close proximity to Earth is too close.

Also ask him questions about asteroids in general. Submit your questions and comments now!

Related: Asteroid flyby: Prepare to duck

Hi Everybody, this is Tom Statler writing from the National Science Foundation in Arlington, Virginia. We're about 5 hours away from the closest approach of 2005 YU55. I'm looking forward to your questions and a fun discussion!

Do we know where this asteroid came from? Has it been flying around our solar system for centuries or did it come from outside our solar system? Is it expected to pass the Earth again in the future or is this just a rare alignment of orbits.

It's been in our Solar System for billions of years, ever since the formation of the planets. It's been orbiting the Sun, just like Earth and the other planets do. Right now it's on an orbit that comes close to Earth's orbit, so the two can pass close to each other, like tonight. This happens frequently.

The story mentions close, 200,000 miles. However it does not mention size or mass.  Will this be big enough and close enough to alter Earths orbit?

It's only about 400 meters across, which is about 1300 feet or the size of a big outlet mall. So that is not nearly big enough to have any effect on Earth's orbit.

I have a 3.5" relector, 900mm...was wondering if I will be able to see it?

That's probably not quite big enough. Remember that the asteroid is just a shopping mall chunk of rock over 200,000 miles away. Not only that, it's about the color of a freshly paved road. So it is not easy to see. Under the best circumstances it will look like nothing more than a faint moving star. The advice from backyard astronomers is that you need at least a 6-inch AND very dark skies.

Is 200,000 miles "close?"

Yeah, 200,000 miles is close by Solar System standards and really close by cosmic standards. This is slightly closer than the Moon. Small asteroids come this close at least once every couple of years. Objects this big come this close only around every 30 years... NOT like clockwork, though.

How long have we known about this asteroid? How much advance notice do we, in general, get regarding these asteroids that are near us?

This asteroid has been known since 2005. Because it does come close to Earth, it was possible to get really precise radar measurements the last time around (April last year). The radar measurements tell us the orbit very precisely and make it certain that THIS object won't be a threat in the foreseeable future. There are special purpose telescopes surveying the sky for asteroids now, and they are discovering several hundred new ones every year. 

Are asteroid & comet orbits consistent in their orbital pathes? Will potential earth colliders have to have been NEOs in the past? When Jupiter (I think) was hit by multiple objects 3 to 5 years (?) ago, what caused the break up of the original object?

That's a fairly deep question. You have to imagine the Solar System in 3D, with every object on its own orbit around the Sun. Asteroid orbits stay the same unless something happens-- like a collision with another body or a passage by a planet that is close enough that the planet's gravity deflects the path. This would put the asteroid on a new orbit that would repeat over and over until the next thing happens. Typically it's millions or tens of millions of years before "things" happening. The disruption of comet SL9 (that impacted Jupiter) was caused by Jupiter's gravity as the result of a very close passage.

This may be a stupid question, but I don't know the answer, so I ask. If one sees an asteroid coming towards them, is there any advice on what one should do, other than pray it misses you? Should one seek to go into a basement or, if there is not time, move into a doorframe?

Well, if you really know it's coming toward YOU, the doorframe ain't gonna help.

Straightforward question here: is this asteroid too close? Should i be worried? what would happen if it did hit earth? because whenever i hear about an asteroid flying by earth i think of the movie armageddon and for someone with an anxiety disorder like me i tend to worry alot.

No, don't worry. Really. This guy could come a lot closer and we wouldn't be worried. It's just a rock. BUT there are other such rocks that could impact in the future, which is why we really need to take advantage of this opportunity to study one of these big fellows up close. This is going to be done by a combination of telescopes worldwide, including the Arecibo radio telescope in Puerto Rico, which is one of NSF's national facilities.

How fast is this asteroid traveling? Will we be able to view it with the naked eye? Will it's movement be perceptible while watching?

I don't know the exact figure, but things in our part of the Solar System are moving about 30 kilometers per second. That's almost exactly the orbital speed of Earth. Call it 20-ish miles per second. Now, Earth and the asteroid are going in the same direction around the Sun, so the RELATIVE speed between the two isn't quite so high, probably around 10 km/sec. If you can catch the asteroid in your telescope or big binocs, the motion should be clearly visible. At its fastest it should cover the width of the Moon in about 3 minutes.

Thanks for taking questions! Is the real-time radar tracking going to be available online? We don't have a telescope big enough to see the asteroid, but it would be fun to know exactly when it's passing. If there was something compatible with Google Earth it would be a fun feature.

That would be fun. I don't think the radar data will be available real time, but I just saw on Sky and Telescope's website ( that the Bellatrix Astronomical Observatory in Italy is doing a live webcast. 

Would this be a good candidate for landing on? I realize it is small in terms of others but it seems we have its path well figured out and reaching it would be almost as easy as the moon?

Close if you time it right, but the speed is a problem. There are better choices that have (at the right moment) low relative velocities compared to Earth.

If we know when another asteroid is approaching closely, could scientists potentially attach data gathering devices to it to collect data from the outer regions of its orbit? The devices could be retrieved on the next pass.

Interesting question... possible in principle but if you have gone to the trouble of building a spacecraft that can get itself onto the same orbit as the asteroid, you might as well just use the spacecraft as your platform. Unless you wanted to see first-hand what happens on the surface of the asteroid over time. That would be extremely cool but challenging and the surface activity would probably be so slow that it would take decades at least to see anything.

I understand this is not our first encounter with YU55, is it getting closer and closer with each pass? When is it visiting again?

No, it's not closer every time. Let's try a race track analogy to help picture this. Take a circular race track with 3 lanes. Visualize Earth as going around the track in the middle lane all the time. The asteroid goes in the inside lane for half way around, then in the outside lane for the other half. Earth goes around in 365 days, the asteroid in 444 (if I remember right). So sometimes we pass close, sometimes not. Basically what's happening now is that we just passed the asteroid as it changes lanes behind us. We're observing it "out the back window" (as it were).

What plans or options (if any) exist for the day that an object is too close or will collide with Earth?

Well, a collision is "too close" but short of that there is not a lot that a hunk of rock can do to you. If the object is small (like 2008 TC3, which landed in the Sudan in 2008 just hours after discovery) then you want to observe it with everything you've got. If it's large enough to do damage, then you hope you know about it far enough in advance to figure out what material properties it has and develop the technology to nudge it JUST enough that it misses.

You mentioned the Arecibo radio telescope earlier. I thought that had been shut down. Or is my information more outdated than I think?

Arecibo is still going strong.

You scientists seem all excited about this asteroid, like a kid with a new toy. But some (most?) of us are worried and anxious. Why are the reactions so different?

Maybe it's because scientists are used to dealing with probabilities and try to bring that into how we deal with risk in our daily lives. This object is not going to hit us. That is certain, so there is no reason to worry about it. But, the chance of a major impact in a human lifetime is somewhere around 1 in 10,000. That's been true for all of human history and we have managed to survive without widespread panic attacks. At the same time that's WAY more likely than being in a plane crash or winning the lottery.

Is there any concern that the close passing of even such a relatively small object could have an impact on high altitude geosynchronous orbiting satellites?

I like this question! Because I don't know the answer! No way it's a danger, but mayyyybeeee it's possible that some satellite orbits could be altered by a millimeter or so. I'll have to look into this later. I could be way off.

What are astronomers most looking to learn from this particular asteroid, if anything?

Oh man, I could write an essay on this but they don't want me to! One thing you can do is observe it simultaneously with visible-light and far-infrared-light telescopes. That tells you about the surface material, how well it conducts heat, which in turn gives you clues as to how porous it is, how strong it is, and so on. Just one example.

Dr. Statler, What material is the asteroid made up of?

Short answer: rock. Longer answer: there are lots of different kinds of asteroids, and we don't have really good information about many of them because big ones don't hit the Earth frequently (lucky for us) and small ones don't survive to the ground unless they are particularly dense. So we don't have any actual meteorite samples of many of the asteroid types.

Looking at the animated trajectory on the NASA site, and it appears that the Moon was in greater danger of a hit than the Earth. What would happen if the Moon sustained a significant hit?

Well no danger to the Moon today. But an object of this size would probably leave a couple-mile-wide crater... of which there are already zillions (that's a technical term) on the Moon's surface. So you wouldn't notice the difference.

What do you personally believe is the origin of the asteroid belt between Mars and Jupiter?

Well, what I personally believe isn't really the issue. The preponderance of the evidence points to the asteroids being leftover material from the formation of the Solar System that didn't end up being incorporated into the planets, their moons, or the Sun. These leftovers have had a complicated history; many have been shattered, probably multiple times, by impacts with each other. One of the most exciting things that has been realized in the last 20 years or so is that how the asteroids are distributed today in the Solar System might tell us about how the planets' orbits may have shifted by huge amounts early in their lives.

Tom, How would you compare the size or weight of this asteroid to that of others, such as the one that supposedly helped destroy the dinosaur population? Is there any way to compare?

This is much smaller. If my memory is right at least 10 times smaller, but don't quote me on that figure.

Will this asteroid flyby be close enough to change the Moon's orbit? Is it close enough to disturb the Earth's spin, and cause more earthquakes?

In order, the answers are: no way, no way, and absolutely no way.

Hi Dr. Statler! What is the most exciting thing for you about this event?

Actually the best thing is that there is so much interest about it. Doing this chat is great! What a wonderful opportunity for everybody to learn about the exciting things that are really happening in the universe. I hope everybody online looks for new opportunities to see the night sky, connect with astronomers through astronomy clubs or your local universities, or just engage with your friends about your love of the natural world.

THANKS to everybody for participating and thanks to the Washington Post for hosting!

In This Chat
Thomas Statler
Dr. Thomas Statler is a Program Director at the National Science Foundation, and Professor of Physics and Astronomy at Ohio University. Dr. Statler is a versatile astrophysicist, an expert on galaxies as well as Solar System dynamics, especially near-Earth asteroids. He has made use of the Hubble Space Telescope and the Chandra X-ray Observatory in space, and ground-based telescopes ranging from the 6.5-meter MMT down to the 4-inch reflector his older brother got for Christmas when they were kids. He has over 20 years of experience teaching both undergraduates and graduate students, mentoring young astronomers, and communicating with the public. For 5 years he wrote a regular astronomy column for the Columbus Dispatch newspaper, and has done numerous radio shows on astronomy.
Recent Chats
  • Next: