This is planetary radio.

This is planetary radio. We hope all of you are enjoying the holidays. I'm Matt Kaplan looking back at the

loss of Columbia this week.

Stay with us for a conversation with Robert Lee Hotes.

The L.A. Times has just published his remarkable series of articles

about what we now know about the tragedy and the amazing work by hundreds if not thousands of people

which has generated this knowledge.

Bruce Betts gives us more good reason to look up in What's up,

up along with our latest trivia contest.

First though, here's Emily returning to answer one of your questions

about that big backyard we call the solar system.

Hi, I'm Emily Lachto-walla with questions and answers. A listener asked,

what are the fastest moving objects in the solar system?

Comets are the solar system's fastest solid bodies.

The speed of a comet depends on the size of its orbit and its proximity to the sun.

An object in space will reach its fastest orbital speed when it passes closest to the Sun at a position in its orbit called

Parahelian among short period comets and asteroids an asteroid called

1995 CR and a comet named Machholz 1 are the fastest.

At Parahelian, both of these objects are 8 times closer to the Sun than the Earth is

and reach speeds above 110 kilometers per second.

You can see animations of both objects on our website at planetary.org.

For comparison, the better known comets, Halle and Hale Bop, reach more leisure leak maximum speeds of only around 50 kilometers per second.

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