Astronomy Picture of the Day 7-16-02

NASA ^ | 7-16-02 | Robert Nemiroff and Jerry Bonnell

[petuniasevan]

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2002 July 16

Outbound from Mercury
Credit: Mariner 10, NASA

Explanation: After just passing Mercury, the robot spacecraft Mariner 10 looked back. The above picture is what it saw. Mercury, the closest planet to the Sun, is heavily cratered much like Earth's Moon. As Mercury slowly rotates, its surface temperature varies from an unbearably cold -180 degrees Celsius in the half facing away from the Sun, to an unbearably hot 400 degrees Celsius in the half facing toward the Sun. Mercury is slightly larger than Earth's Moon and much denser. The Mariner 10 spacecraft swooped by Mercury three times in its journey around the inner Solar System in the mid-1970s. This outbound view has similarities to the inbound view. Nearly half of Mercury's surface has yet to be photographed in detail.

[petuniasevan]

Astronomy Fun Fact:

Mercury is tidally locked into a 3:2 rotation to revolution synchronization. Until radar studies in 1965 proved otherwise, it was believed that Mercury kept the same face to the sun always (like the moon does to the Earth).

MESSENGER is a MErcury Surface, Space ENvironment, GEochemistry and Ranging mission to orbit Mercury following two flybys of that planet. Launch Window: 10-Mar - 29-Mar-2004 12-May - 23-May-2004 Venus Flyby 1: 24-Jun-2004 Venus Flyby 2: 16-Mar-2006 Mercury Flyby 1: 21-Jul-2007 Mercury Flyby 2: 11-Apr-2008 Enter Mercury Orbit: 06-Apr-2009

Get on the APOD PING list!

[petuniasevan]

APOD PING!

Sorry it's late. Plumbing emergency.

[RightWhale]

What are the white lines in the surface? Cracks due to tidal stresses, or has Mercury had a rough life, getting slammed by some larger sized asteroids? Or are they ejecta trails from not-quite-so-large impacts?

[2Trievers]

A cure all for those lines and wrinkles ... &;-)

[2Trievers]

Thanks for your loyalty 'tunia. You have us like Pavlov's dogs out here! LOL &;-)

[MozartLover]

"Sorry it's late. Plumbing emergency."

I hate those.

Thanks for another goodie.

[petuniasevan]

You're welcome. Poorman is putting a new flange down for the upstairs toilet as I write this.
Hope THIS technique works. The downstairs ceiling is soggy...

[petuniasevan]

Some look like ejecta; others, who knows?
Hopefully MESSENGER will provide some answers in a few years.

[RightWhale]

Long range plan. Move Venus farther out from the sun, perhaps into a stable orbital configuration with earth, and terraform. Move Mercury into orbit around Venus.

[NerdDad]

I'll second that. Clarinet_King (my 17 y/o) called me at work twice yesterday to ask if I had gotten my APOD yet. He was simply beside himself because he hadn't had his daily fix. He'll be pleasantly surprised this morning when he drags his lazy carcass out of bed.

[2Trievers]

Sounds like a great kid ... hug him for me! Naw ... second thought, he'd rather die first, or be hit by a meteor! LOL &;-)

[MeekOneGOP]

Thanks, bump!

[foolish-one]

Worth the wait.

[headsonpikes]

Great ideas!

And what do you propose to do in the afternoon?

[RightWhale]

We have to have this accomplished by 2050 according to the godless greenies. They say we need two more planets. This gives us one more. This afternoon we should look for a second planet. The godless greenies have already put Mars off-limits, thereby raising the bar.

[NerdDad]

You're right about the hug thing. His mom can't even guilt him into one anymore. He is a good kid. I'm awful proud of him, but I'm supposed to keep that a secret too. Kind of like hugging. I was especially proud when he asked me to help him sign up for his own Freeper account a few days ago. Now we just need to get him to pony up at Freepathon time. It will be another proud day this November when I walk into the polls with him for the very first time. I'm liable to get in trouble for causing a scene because I plan to introduce him and tell folks how proud I am to have him with me.

[2Trievers]

I'll see what I can do to get you an eighth day to the week. Ya' think that will help? &;-)

[2Trievers]

Hug him in public! It's your job! My guys 20, 22, 24 still hate it. Good! That means we're all doing our jobs! LOL &;-)

[RightWhale]

What is needed is a planetary engineer. Know of any?

[2Trievers]

Sleavester can talk his way into any position ... but he's out of town right now. He'd take the job ... I know he's had a lot of domestic engineering experience ... I'll have him forward his resume to you! &;-)