Take a Look: Huge Asteroid to Fly By Earth in November

Article written: 3 May , 2011
Updated: 24 Dec , 2015


A large space rock will pass close to Earth on November 8, 2011 and astronomers are anticipating the chance to see asteroid 2005 YU55 close up. Just like meteorites offer a free “sample return” mission from space, this close flyby is akin to sending a spacecraft to fly by an asteroid – just like how the Rosetta mission recently flew by asteroid Lutetia – but this time, no rocket is required. Astronomers are making sure Spaceship Earth will have all available resources trained on 2005 YU55 as it makes its closest approach, and this might be a chance for you to see the asteroid for yourself, as well.

“While near-Earth objects of this size have flown within a lunar distance in the past, we did not have the foreknowledge and technology to take advantage of the opportunity,” said Barbara Wilson, a scientist at JPL. “When it flies past, it should be a great opportunity for science instruments on the ground to get a good look.”

2005 YU55 is about 400 meters [1,300 feet] wide, and closest approach will be about 325,000 kilometers (201,700 miles) from Earth.

“This is the largest space rock we have identified that will come this close until 2028,” said Don Yeomans, manager of NASA’s Near-Earth Object Program Office at JPL, and Yeomans assured that we are in no danger from this asteroid.

“YU55 poses no threat of an Earth collision over, at the very least, the next 100 years,” he said. “During its closest approach, its gravitational effect on the Earth will be so miniscule as to be immeasurable. It will not affect the tides or anything else.”

Astronomers estimate that asteroids the size of YU55 come this close to Earth about every 25 years. We just haven’t had this much advance warning – a testament to the work that Yeomans and his team does at the NEO Program in detecting asteroids and detecting them early.

So, here’s a chance for a close-up look. The 70-meter (230-foot) newly upgraded Goldstone antenna in California, part of NASA’s Deep Space Network, will be imaging the asteroid with radar.

“Using the Goldstone radar operating with the software and hardware upgrades, the resulting images of YU55 could come in with resolution as fine as 4 meters per pixel,” said Benner. “We’re talking about getting down to the kind of surface detail you dream of when you have a spacecraft fly by one of these targets.”

Combining the radar images with ground-based optical and near-infrared observations, astronomers should get a good overview of one of the larger near-Earth objects.

Look for more information in the near future about observing campaigns for amateur astronomers of this object. At first, 2005 YU55 will be too close to the sun and too faint for optical observers. But late in the day (Universal Time) on Nov. 8, and early on Nov. 9, the asteroid could reach about 11th magnitude for several hours before it fades as its distance rapidly increases.

This radar image of asteroid 2005 YU55 was generated from data taken in April of 2010 by the Arecibo Radar Telescope in Puerto Rico. Image credit: NASA/Cornell/Arecibo

2005 YU55 was discovered in December 2005 by Robert McMillan, head of the NASA-funded Spacewatch Program at the University of Arizona, Tucson. In April 2010, Mike Nolan and colleagues at the Arecibo Observatory in Puerto Rico generated some ghostly images of 2005 YU55 when the asteroid was about 2.3 million kilometers (1.5 million miles) from Earth.

“The best resolution of the radar images was 7.5 meters [25 feet] per pixel,” said JPL radar astronomer Lance Benner. “When 2005 YU55 returns this fall … the asteroid will be seven times closer. We’re expecting some very detailed radar images.”

Radar antennas beam directed microwave signals at their celestial targets — which can be as close as our moon and as far away as the moons of Saturn. These signals bounce off the target, and the resulting “echo” is collected and precisely collated to create radar images, which can be used to reconstruct detailed three-dimensional models of the object. This defines its rotation precisely and gives scientists a good idea of the object’s surface roughness. They can even make out surface features, and astronomers hope to see boulders and craters on the surfaces of 2005 YU55, as well as detailing the mineral composition of the asteroid.

“This is a C-type asteroid, and those are thought to be representative of the primordial materials from which our solar system was formed,” said Wilson. “This flyby will be an excellent opportunity to test how we study, document and quantify which asteroids would be most appropriate for a future human mission.”
Yeomans said this is a great opportunity for scientific discovery. “So stay tuned. This is going to be fun.”

Source: JPL

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7 Responses

  1. gopher65 says

    This is great:). It’s just too bad they hadn’t orchestrated a quick, cheap sample return mission while it is here. Mind you, it would be pretty hard to match velocities with that thing.

  2. diatoms says

    If it did hit the earth, (purely hypothetical), what would be the size of the crater it would produce?

    • brundall says

      According to this impact calculator:


      A 400 meter asteroid, consisting of dense rock, travelling @ 17km/s and hitting the earth (sedimentary rock) at a 45 degree angle would produce an initial crater of 5.11km in diameter and a final crater of 6.36km.

  3. Lawrence B. Crowell says

    The orbital path is nearly perpendicular to the orbit of the Earth around the sun, and moving rather rapidly. That must be a rather eccentric orbit this asteroid is on. Of course the appearance of this perpendicularity is due to the fact this is on the frame coincident with the Earth. By eyeballing the image with a ruler and making some calculations it appears to pass through the Earth-moon system at about 10km/sec relative to the Earth’s frame. The Earth’s orbital velocity around the sun is 29.5km/sec, and so by comparison this suggests a pretty eccentric orbit.


  4. Olaf says

    It is also moving above Earth-Moon plane.
    A simulation I did was that it moved with 13.71 km/s relative to earth at its closest point around 0.002264 AU.

    What would be the minimal speed be relative to Earth at that closest distance to actually let it fall to Earth? It must be lower than a circular orbital speed.

  5. Zephyr says

    Too bad President Obama set 2025 as a target for visiting an asteroid, We haven’t got a spare Apollo rocket to go with Skylab B? He could ox cart it, create a vehicle with the specific intent to http://en.wikipedia.org/wiki/Space_rendezvous with the asteroid. Or a small Orbiter with beacon.

    Pioneer 10 and 11 technology communicates from outside the solar system, you might need a Lagrange relay satellite or two, sadly I don’t think Ulysses or any of the solar observation swarm are tasked as relay sate. The power of Hind site, 20 20.

    Come to think about it, how expensive would a pathfinder or spirit Rover be? New Horizons took 8 hours to cover the distance, you could include a small cube sat swarm, fully map and sample. Great Target of opportunity. it would be a great challenge.

  6. julien alien says

    So if all goes well and the organization that hired this bright eyed boy in Puerto Rico is not lying,then we should all be fine.I was looking at the projection map and couldn’t help but notice that even though it passes too close to the moon for comfort,it might pull the moon further or wobble it if calculations are wrong(purposely…I don’t trust N.A.S.A.)It would take a long time to reset the moon’s orbit if it was disturbed and this could result in exaggerated tides along with unwanted volcanic activity.Mass extinction.I think it will be O.K. though.Send unwanted k-rations to jefffersonlures.com

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