The image is the first topographic map of part of Titan's north polar region. The false-color mosaic on the left was produced from overlapping stereo images from the Cassini radar instrument and Phobos and Deimos, the moons of Mars, are seen in this movie put together from 19 images taken by Mars Odyssey's camera.
Mars Odyssey Observes Martian Moons. This is the separate version of the infrared image that accompanies the feature Cassini Sees Saturn Storm's Explosive Power The visible-light image can be seen separately here: Catching Its Tail To celebrate the first anniversary of Cassini's arrival at Saturn, you were invited to vote on a selection of the most popular images so far.
The most popular image was announced in mid-July, This graphic illustrates how scientists on NASA's Cassini mission think water interacts with rock at the bottom of the ocean of Saturn's icy moon Enceladus, producing hydrogen gas H2. Enceladus Hydrothermal Activity. Cassini mission planners created this animation to showcase Cassini's final 22 orbits - the mission's Grand Finale. Grand Finale Orbits - Side View. Regions of Saturn's Magnetosphere Click here for high resolution version.
Regions of Saturn's Magnetosphere. This still is from a short computer-animated film that highlights Cassini's accomplishments and Saturn and reveals the science-packed final orbits between April and September Orbit Insertion. Pioneer and Voyager trajectories through the early s.
Pioneer Trajectories. By convention, mountains on Titan are named for mou Mountains of Titan. Some key numbers for Cassini's Grand Finale and final plunge into Saturn. The forceful storm generated unprecedented spikes in temperature and increased amounts of ethylene. In fact, all the cometary material continues to orbit the Sun. However, a wind made up of charged particles from the Sun blows past the comet and pushes charged particles from the comet away from the comet.
This is how we discovered the existence of the "solar wind. The ion tail is straight. The dust tail is curved. Meteor showers are short term events in which we witness a large number a few per minute of "shooting stars" for several hours.
Shooting stars are small grains of dust that are swept up into the Earth's atmosphere as Earth orbits the Sun. The collision is quite violent and tears the dust grain apart into molecules. What do you see when you witness a shooting star? You are seeing a trail of glowing sodium atoms in the upper atmosphere. These atoms are not ones ripped off the interplanetary dust particle IDP ; rather, these are atoms resident in the Earth's atmosphere that are heated and glow due to friction with the passing IDP.
Why meteor "showers"? All meteor showers are associated with the orbital paths of short-period comets. With each passage near the Sun, material stripped off the comet becomes a long, wide stream of particles orbiting the Sun, following in the orbital path of the comet.
If the comet's orbit literally intersects the Earth's orbit, then every year the Earth will carve a path through the dust debris left behind by the comet. We can observe comets before they develop their tails, when they are still in the outer solar system.
We also have flown spacecraft past three comets, including Halley, and measured directly the sizes of their nuclei. As a rule of thumb, comets are about 10 km in diameter. Halley is about 16 x 8 x 8 km; Hale-Bopp was one of the biggest comets every seen, with a diameter twice that of Halley. But the typical comet is about 10 km in size, but of course is odd shaped since such small objects will not be spherical shaped.
And in , the Deep Impact collider smashed into the Comet Temple 1 to study the guts of the comet's nucleus. Photographs from comet missions have revealed that comet nuclei are quite small, ranging from less than a mile to tens of miles across. Some of them also have irregular shapes, sometimes resembling the end of a dumbbell.
On Earth and other spherical bodies, gravity is directed straight down. But if you were on a dumbbell-shaped comet, gravity might pull you down and to the side, depending on where you were standing, Moorhead told Space.
However, that gravitational tug wouldn't be overwhelmingly strong. The gravity of Halley's Comet, for example, is about equal to the gravity of Mount Everest if you were to remove the mountain from Earth and deposit it in space — if you were to drop an object from chest level, it would take about two minutes to hit the ground.
Comets, particularly the irregularly shaped ones, could offer up interesting features to explore, such as impact craters or cavities formed from the sublimation of material. But you'd likely get bored rather quickly. Lanai is about
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