Showing posts with label jupiter. Show all posts
Showing posts with label jupiter. Show all posts
Tuesday, February 8, 2011
Tuesday, September 28, 2010
Saturday, July 24, 2010
Massive Comet Impact Detected on Neptune
Smashup 200 years ago suggests crashes more frequent than thought. Rachel Kaufman for National Geographic News | July 23, 2010
Neptune was struck by a giant comet about two centuries ago, according to new research. The find adds to a growing body of evidence that cometary collisions with gas giant planets may be more common than astronomers thought.
On rocky planets with thin atmospheres, such as Mercury (pictures) and Mars, it's easy to count the craters made by impacts dating back millions of years, giving scientists a rough estimate of how frequently space rocks collide with other worlds.
But the gas giants—Jupiter, Saturn, Uranus, and Neptune—are planets that are almost all roiling atmosphere with just tiny cores of rock, making it much harder to find evidence of past impacts.
In 1994 the comet Shoemaker-Levy 9 broke apart and smashed into Jupiter, and several space probes, including Voyager 2, Galileo, and the Hubble Space Telescope, were able to document the rare event.
Using what they'd learned about chemicals left in Jupiter's atmosphere after the comet crash, scientists from the French observatory LESIA and the Max Planck Institutes in Germany analyzed the composition of Neptune's atmosphere with the European research satellite Herschel.
The data show that the amount of carbon monoxide in Neptune's upper atmosphere is higher than in the planet's lower atmosphere. Since gas would normally thin out as it reaches higher atmospheric layers, the extra gas had to come from some outside source, the scientists say.
A comet, which carries carbon monoxide in its icy tail, is the "main explanation," said study co-author Paul Hartogh of the Max Planck Institute for Solar System Research.
Comet Also Smashed Saturn?
The researchers estimate the comet that struck Neptune was 1.2 miles (2 kilometers) wide, which would have made its impact very powerful.
The first fragment of Shoemaker-Levy 9 was just half the size of the unnamed Neptune comet. When the fragment struck Jupiter, it released energy equal to 225,000 megatons of TNT and created a plume 621 miles (1,000 kilometers) high.
In addition, a similar technique used earlier this year found evidence for a comet crash on Saturn 300 years ago.
Adding the Neptune find to the relatively recent Saturn and Jupiter smashups implies that comet collisions might be more frequent than astronomers had thought.
A 1997 study estimated that comets about a mile (1.6 kilometers) wide hit Jupiter once every 6,000 years. And mathematical models for Neptune have suggested that a major comet hits the gas giant planet every 8,000 years, Hartogh said.
Based on the old calculations, he said, "statistically, it's not so probable" that Neptune, Jupiter, and Staurn would each suffer a major impact event within a 300-year period—suggesting a new estimate may be in order.
"Maybe there are more impacts than we think."
Neptune was struck by a giant comet about two centuries ago, according to new research. The find adds to a growing body of evidence that cometary collisions with gas giant planets may be more common than astronomers thought.
On rocky planets with thin atmospheres, such as Mercury (pictures) and Mars, it's easy to count the craters made by impacts dating back millions of years, giving scientists a rough estimate of how frequently space rocks collide with other worlds.
But the gas giants—Jupiter, Saturn, Uranus, and Neptune—are planets that are almost all roiling atmosphere with just tiny cores of rock, making it much harder to find evidence of past impacts.
In 1994 the comet Shoemaker-Levy 9 broke apart and smashed into Jupiter, and several space probes, including Voyager 2, Galileo, and the Hubble Space Telescope, were able to document the rare event.
Using what they'd learned about chemicals left in Jupiter's atmosphere after the comet crash, scientists from the French observatory LESIA and the Max Planck Institutes in Germany analyzed the composition of Neptune's atmosphere with the European research satellite Herschel.
The data show that the amount of carbon monoxide in Neptune's upper atmosphere is higher than in the planet's lower atmosphere. Since gas would normally thin out as it reaches higher atmospheric layers, the extra gas had to come from some outside source, the scientists say.
A comet, which carries carbon monoxide in its icy tail, is the "main explanation," said study co-author Paul Hartogh of the Max Planck Institute for Solar System Research.
Comet Also Smashed Saturn?
The researchers estimate the comet that struck Neptune was 1.2 miles (2 kilometers) wide, which would have made its impact very powerful.
The first fragment of Shoemaker-Levy 9 was just half the size of the unnamed Neptune comet. When the fragment struck Jupiter, it released energy equal to 225,000 megatons of TNT and created a plume 621 miles (1,000 kilometers) high.
In addition, a similar technique used earlier this year found evidence for a comet crash on Saturn 300 years ago.
Adding the Neptune find to the relatively recent Saturn and Jupiter smashups implies that comet collisions might be more frequent than astronomers had thought.
A 1997 study estimated that comets about a mile (1.6 kilometers) wide hit Jupiter once every 6,000 years. And mathematical models for Neptune have suggested that a major comet hits the gas giant planet every 8,000 years, Hartogh said.
Based on the old calculations, he said, "statistically, it's not so probable" that Neptune, Jupiter, and Staurn would each suffer a major impact event within a 300-year period—suggesting a new estimate may be in order.
"Maybe there are more impacts than we think."
Sunday, July 18, 2010
All the other planets in our solar system nearly aligned perfectly this morning
I was out looking at the stars this morning and I noticed that currently (and for the next few weeks I guess) Jupiter is the brightest celestial object in the sky, after the moon and sun, of course. So, I came in and opened my favorite planetarium program, Stellarium, to see what else was out there, and I noticed that every planet in the solar system, plus the moon and sun were as close to perfect alignment as I've ever seen. Even some of the other objects in our solar system past Pluto were aligned (of course, Pluto was the planet farthest from alignment.) I took some screen shots:
And in this image, (l to r) you can see the Sun, Jupiter and Uranus right together, Neptune, and then there's Pluto off kilter to the far right. Click the image to make it larger. In this image, I'm zoomed about the same distance but with a wider field of vision to fit the Sun in the same image with this grouping of planets.
Anyway, it was something which doesn't happen very often that I thought was cool and I wanted to share. Since they aren't perfectly aligned, I guess that's why nothing has really been written about this--that I have seen. But that's pretty dang close to perfect alignment, if you ask me!
In this image, you can see (from l to r): the Moon, Saturn, Mars, Vesta (one of those objects past Pluto), Venus, Mercury, the Sun, and Juno (another object past Pluto, quite a bit off, but in the picture). Click the image to make it larger. The planetary orbits are the red lines. I'm zoomed quite a bit out to see the big picture.
Anyway, it was something which doesn't happen very often that I thought was cool and I wanted to share. Since they aren't perfectly aligned, I guess that's why nothing has really been written about this--that I have seen. But that's pretty dang close to perfect alignment, if you ask me!
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