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What's closer than the Moon?

We're used to thinking of the Moon as our closest neighbor, but for a little while today, that won't be true. An asteroid with the charming name YU55 (pronounced either "you" or "why you?") will be passing within 201,700 miles of Earth. For reference, that's about 25 Earth-diameters away, while the Moon is about 30 Earth-diameters away.

Left, a radar-generated image of YU55's adorable
little face. Right, its roller coaster ride.


YU55 has passed close to Earth before, but this is the closest it's ever come, and the closest it will come for a long time in the future.

This asteroid was only discovered six years ago by SpaceWatch, an organization that is an example of why astronomy is important to your life--because you might as well know about an asteroid before it crushes your house.

Aside from an excuse to go outside and look up tonight (with at least a 6-inch telescope, if you hope to see this aircraft carrier of an asteroid), this close encounter provides an important opportunity for scientists to learn more about YU55 specifically, asteroids in general, and the composition of the early solar system.

The asteroid will be traveling from Aquila to Pegasus starting around 6:30 Eastern.
Check out a SkyMap to see what this means for where to point
your large personal telescope.

Here in Green Bank, Dr. Michael Busch is using the Green Bank Telescope to measure the temperature, and how much energy it takes to change the temperature, of the material below the asteroid's surface.

Objects in space emit radio waves for different reasons, and one of those reasons is because they are warm. The characteristics of these warm waves--called thermal emission--are different depending on the temperature of the object. By looking at different thermal wavelengths and seeing how the brightness changes, astronomers can determine what temperature an object would have to be to emit in that particular way.

Busch will additionally be taking radar data on the asteroid. A radar in Arecibo, Puerto Rico, will transmit toward the asteroid, which will be so close that the light will arrive in only 2.4 seconds. The light will bounce off the asteroid and all its contours and crevices. The Green Bank Telescope will receive the echoed signal, providing us (after lots of processing) with an image of the asteroid's shape and the details of how it is spinning.

For more information about this asteroid and what different telescopes are doing since YU55 is not going to hit the Earth and destroy them, see NRAO Science Writer Tania Burchell's post.

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    Response: Bluewave
    What's closer than the Moon? - Blog - Smaller Questions
  • Response
    Technology gives you a front line experience in understanding other culture. This might come in handy for a student who studies this subject as it will helps him in understanding his subject by communicating with them.
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    Response: 压瓦机生产线
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    Response: gmail.com sign in
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  • Response
    Response: EduBirdie Reviews
    I too use think that moon is the closest body to the earth. But, after reading this article I came to know that what I am thinking till this date is false and there is another body which is closest to earth than moon. It is good educational article which thought ...

Reader Comments (1)

thanks for sharing that

July 20, 2015 | Unregistered Commentermoha

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