Astronomy Picture of the Day 10-19-02

NASA ^ | 10-19-02 | 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 October 19

Io's Surface: Under Construction
Credit: Galileo Project, JPL, NASA

Explanation: Like the downtown area of your favorite city, the roads you drive to work on, and any self-respecting web site ... Io's surface is constantly under construction. This moon of Jupiter holds the distinction of being the Solar System's most volcanically active body -- its bizarre looking surface continuously formed and reformed by lava flows. Generated using 1996 data from NASA's Galileo spacecraft, this high resolution composite image of Io is centered on the side of Io that always faces away from Jupiter. It has been enhanced to emphasize Io's surface brightness and color variations, revealing features as small as 1.5 miles across. The notable absence of impact craters suggests that the entire surface is covered with new volcanic deposits much more rapidly than craters are created. What drives this volcanic powerhouse? A likely energy source is the changing gravitational tides caused by Jupiter and the other Galilean moons as Io orbits the massive gas giant planet. Heating Io's interior, the pumping tides would generate the sulfurous volcanic activity.

[petuniasevan]

Astronomy Fun Fact:

Io is about 2275 miles in diameter. Our own moon is about 2160 miles in diameter. If Io were to replace our moon, its size would be almost the same. Its appearance would be greatly different. It would be seven to eight times brighter in the night sky than our present moon.

[petuniasevan]

[glock rocks]

wow, why do you suppose it would appear so much brighter?

[petuniasevan]

Our moon only reflects 7-10% of the light that hits it. Its surface is the color of a half-used charcoal briquet.

Io's surface is much more reflective. Its surface is pale yellow/white from sulfur dioxide.

[PatrickHenry]

Bump.

[RadioAstronomer]

I have friends who were on the Galileo flight team. :-)

[AngrySpud]

Are changes discernable from year-to-year, or would it be century-to-century?

[RightWhale]

Are changes discernable from year-to-year

Volcanic, sometimes day to day. Sulfur is nice-looking, but not real pleasant to have around. Io might be great for mining, but not popular as a tourist resort. The greenies might try to make it a national park, thinking Yellowstone, but this one isn't another Yellowstone; it more resembles apocalytic descriptions of what will happen to political enemies in the afterlife.

[longshadow]

That surface looks like the worse case of teen-age acne I've ever seen. How will Io ever get a date?

[mikrofon]

That's OK, I prefer the smell of cheese to rotten eggs anyway... ;^)

It's a good thing for astro viewing that the moon's albedo isn't 8-10x greater -- even a relatively thin crescent would obliterate much of the deep sky stuff.

Neat pic as always!

[bluefish]

From a non-astronomy type dude, all I can say is it looks like our moon, but with a horrible "skin" disease.

[BenLurkin]

Io is indeed a hellish place.

[Aracelis]

I have friends who were on the Galileo flight team.

Wow! They must have been very small! ;-)

[Aracelis]

Egads! An image of my brain post-finals!

[wafflehouse]

ive found oranges in my fridge that look very much like Io

[Consort]

Io should be renamed to Solaris since the surface is constantly changing.