New Horizons flew by our favorite dwarf planet in July and scientists continue to uncover surprising details about this faraway world. Now available: 6-inch globe of Pluto created using New Horizons imagery! Community Leaders: Notable Astronomers. By: Richard S. Wright Jr.
November 9, October 19, By: Monica Young September 28, Solar System. Earth has fewer impact craters than Mercury and the Moon too. Is this for the same reason that Venus has fewer impact craters? The environment is too harsh for a rover to go there.
It is even more difficult for students to figure out the geological history of a distant planet based on the information given here. Still we can piece together a few things. Much of the volcanic activity is caused by plate tectonic activity. But on Venus, there is no evidence of plate boundaries and volcanic features do not line up the way they do at plate boundaries. Scientists think that there is frequent, planet-wide resurfacing of Venus with volcanism taking place in many locations.
The cause is heat that builds up below the surface that has no escape until finally it destroys the crust and results in volcanoes. Mars is a quite different from Earth and yet more similar than any other planet. Mars is smaller, colder, drier, and appears to have no life, but volcanoes are common to both planets and Mars has many.
Mars is easy to observe so Mars has been studied more thoroughly than any other extraterrestrial planet. Space probes, rovers, and orbiting satellites have all yielded information to planetary geologists. Viewed from Earth, Mars is reddish in color. The ancient Greeks and Romans named the planet after the god of war. But the surface is not red from blood but from large amounts of iron oxide in the soil. Although the atmosphere is made up mostly of carbon dioxide, the planet has only a weak greenhouse effect so temperatures are only slightly higher than if the planet had no atmosphere.
Mars has mountains, canyons, and other features similar to Earth. Some of these surface features are amazing for their size! Olympus Mons is a shield volcano, similar to the volcanoes that make up the Hawaiian Islands.
But Olympus Mons is also the largest mountain in the solar system Figure below. Olympus Mons is about 27 km Mars also has the largest canyon in the solar system, Valles Marineris Figure below. Valles Marineris is 4, km 2, mi long, as long as Europe is wide, and one-fifth the circumference of Mars.
The canyon is 7 km 4. By comparison, the Grand Canyon on Earth is only km mi long and about 2 km 1. Mars has more impact craters than Earth, though fewer than the Moon. Water cannot stay in liquid form on Mars because the atmospheric pressure is too low. However, there is a lot of water in the form of ice and even prominent ice caps Figure below. Scientists also think that there is a lot of water ice present just under the Martian surface. This ice can melt when volcanoes erupt, and water can flow across the surface temporarily.
Scientists think that water once flowed over the Martian surface because there are surface features that look like water-eroded canyons Figure below. The presence of water on Mars, even though it is now frozen as ice, suggests that it might have been possible for life to exist on Mars in the past.
Mars has two very small moons that are irregular rocky bodies Figure below. Phobos and Deimos are named after characters in Greek mythology — the two sons of Ares, who followed their father into war. Ares is equivalent to the Roman god Mars. Mars has two small moons, Phobos left and Deimos right. Both were discovered in and are thought to be captured asteroids.
The Mars Science Laboratory was launched on November 26, and will search for any evidence that the Red Planet was once capable of supporting life. Curiosity is a car-sized rover that is scouring the red planet for clues; it landed in August Why do the temperatures on some planets vary widely?
Why are some temperatures much less variable? Suppose you are planning a mission to Mars. Identify two places where you might be able to get water on the planet. Why is this important? Skip to main content. Conventional wisdom is that the young Sun blew the gases into the outer fringes of the Solar System and that is why there are such large gas giants there.
The four inner planets are called terrestrial planets because their surfaces are solid and, as the name implies, somewhat similar to Earth — although the term can be misleading because each of the four has vastly different environments. Below are brief descriptions of each of these planets based on this information from NASA. Mercury: Mercury is the smallest planet in our Solar System and also the closest. It rotates slowly 59 Earth days relative to the time it takes to rotate around the sun 88 days.
The planet has no moons, but has a tenuous atmosphere exosphere containing oxygen, sodium, hydrogen, helium and potassium. Venus: Venus was once considered a twin planet to Earth, until astronomers discovered its surface is at a lead-melting temperature of degrees Fahrenheit degrees Celsius. The planet is also a slow rotator, with a day long Venusian day and an orbit around the sun at days. Its atmosphere is thick and contains carbon dioxide and nitrogen.
Earth: Earth is the only planet with life as we know it, but astronomers have found some nearly Earth-sized planets outside of our solar system in what could be habitable regions of their respective stars. It contains an atmosphere of nitrogen and oxygen, and has one moon and no rings. Many spacecraft circle our planet to provide telecommunications, weather information and other services.
Mars: Mars is a planet under intense study because it shows signs of liquid water flowing on its surface in the ancient past.
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