By continuing to use our website you consent to all cookies in accordance with our cookie policy. Share on Facebook. Share on Twitter. One hemisphere is cooling faster than the other. By Benjamin Taub 19 Mar , Smaller planets cool faster than larger planets because smaller planets have a larger surface area to volume ratio. The stage of cooling of a planet plays an important role in the geologic activity of that planet. Earth, a large planet, is hot and has active volcanos and plate tectonics at its surface.
In its interior, motion in its liquid outer core generates a magnetic field. This magnetic field shields Earth's surface from the charged particles of the solar wind, protecting our atmosphere and surface. The Moon, a small satellite of Earth, has cooled completely and no longer has active volcanism or a magnetic field. Mars, intermediate in size between Earth and the Moon, has not cooled completely, and has few, possibly still active, volcanos. The containers need to be made of the same material and be the same shape.
Access to warm water For the Facilitator: Background information Preparation If you are using objects to aid in the discussion, place them in a central location that is clearly visible to all the children. Activity 1. Have all the planets cooled the same amount — are they all the same temperature on the inside today? What might control how much a planet has cooled on the inside?
Answers will vary, but may include what it is made of or its size. Some children may say "how close a planet is to the Sun will control its temperature; remind them that you are thinking about how warm the planet is on the inside, not the surface where the Sun shines. What evidence might a planetary scientist use to suggest that a planet is still warm?
Answers will vary, but may include whether or not a planet has active volcanos. What is the same — or different — about them? One Mercury solar day one full day-night cycle equals Earth days — just over two years on Mercury. Mercury's axis of rotation is tilted just 2 degrees with respect to the plane of its orbit around the Sun. That means it spins nearly perfectly upright and so does not experience seasons as many other planets do. Mercury formed about 4. Like its fellow terrestrial planets, Mercury has a central core, a rocky mantle, and a solid crust.
Mercury is the second densest planet, after Earth. It has a large metallic core with a radius of about 1, miles 2, kilometers , about 85 percent of the planet's radius. There is evidence that it is partly molten or liquid. Mercury's outer shell, comparable to Earth's outer shell called the mantle and crust , is only about kilometers miles thick.
Mercury's surface resembles that of Earth's Moon, scarred by many impact craters resulting from collisions with meteoroids and comets. Craters and features on Mercury are named after famous deceased artists, musicians, or authors, including children's author Dr. Seuss and dance pioneer Alvin Ailey. Very large impact basins, including Caloris miles or 1, kilometers in diameter and Rachmaninoff miles, or kilometers in diameter , were created by asteroid impacts on the planet's surface early in the solar system's history.
While there are large areas of smooth terrain, there are also cliffs, some hundreds of miles long and soaring up to a mile high. They rose as the planet's interior cooled and contracted over the billions of years since Mercury formed. Most of Mercury's surface would appear greyish-brown to the human eye. The bright streaks are called "crater rays. The tremendous amount of energy that is released in such an impact digs a big hole in the ground, and also crushes a huge amount of rock under the point of impact.
Some of this crushed material is thrown far from the crater and then falls to the surface, forming the rays. However, since this world doesn't have much of a real atmosphere to entrap any heat, at night temperatures can plummet to minus degrees Fahrenheit minus degrees Celsius , a temperature swing of more than 1, degrees Fahrenheit degrees Celsius , the greatest in the solar system.
Mercury is the smallest planet — it is only slightly larger than Earth's moon. Since it has no significant atmosphere to stop impacts, the planet is pockmarked with craters. About 4 billion years ago, an asteroid roughly 60 miles km wide struck Mercury with an impact equal to 1 trillion 1-megaton bombs, creating a vast impact crater roughly miles 1, km wide. Known as the Caloris Basin, this crater could hold the entire state of Texas.
Another large impact may have helped create the planet's odd spin , according to research in Comets or meteorites may have delivered ice there, or water vapor may have outgassed from the planet's interior and frozen out at the poles. Average distance from the sun: 35,, miles 57,, km. By comparison: 0. Perihelion closest approach to sun : 28,, miles 46,, km.
Aphelion farthest distance from sun : 43,, miles 69,, km. As if Mercury isn't small enough, it not only shrank in its past but is continuing to shrink today, according to a report. The tiny planet is made up of a single continental plate over a cooling iron core. As the core cools, it solidifies, reducing the planet's volume and causing it to shrink.
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