1. Our solar system is made up of the sun and everything that travels around it. This includes eight planets and their natural satellites such as Earth's moon; dwarf planets such as Pluto and Ceres; asteroids; comets and meteoroids 2. The sun is the center of our solar system. It contains almost all of the mass in our solar system and exerts a tremendous gravitational pull on planets and other bodies. 3. Our solar system formed about 4.6 billion years ago.
4. The four planets closest to the Sun - Mercury, Venus, Earth, and Mars - are called the terrestrial planets because they have solid, rocky surfaces. 5. Two of the outer planets beyond the orbit of Mars - Jupiter and Saturn - are known as gas giants; the more distant Uranus and Neptune are called ice giants. 6. Most of the known dwarf planets exist in an icy zone beyond Neptune called the Kuiper Belt, which is also the point of origin for many comets. 7. Many objects in our solar system have atmospheres, including planets, some dwarf planets and even a couple moons. 8. Our solar system is located in the Orion Arm of the Milky Way Galaxy. There are most likely billions of other solar systems in our galaxy. And there are billions of galaxies in the universe. 9. We measure distances in our solar system by Astronomical Units (AU). One AU is equal to the distance between the sun and the Earth, which is about 150 million km (93 million miles). 10. NASA's twin Voyager 1 and Voyager 2 spacecraft are the first spacecraft to explore the outer reaches of our solar system
1. Mercury is the smallest planet in our solar system - only slightly larger than the Earth's moon. 2. It is the closest planet to the sun at a distance of about 58 million km (36 million miles) or 0.39 AU. 3. One day on Mercury (the time it takes for Mercury to rotate or spin once) takes 59 Earth days. Mercury makes a complete orbit around the sun (a year in Mercury time) in just 88 Earth days. 4. Mercury is a rocky planet, also known as a terrestrial planet. Mercury has a solid, cratered surface, much like Earth's moon. 5. Mercury's thin atmosphere, or exosphere, is composed mostly of oxygen (O2), sodium (Na), hydrogen (H2), helium (He), and potassium (K). Atoms that are blasted off the surface by the solar wind and micrometeoroid impacts create Mercury's exosphere. 6. Mercury has no moons.
7. There are no rings around Mercury.
8. Only two spacecraft have visited this rocky planet: Mariner 10 in 1974-5 and MESSENGER, which flew past Mercury three times before going into orbit around Mercury in 2011. 9. No evidence for life has been found on Mercury. Daytime Temperatures can reach 430 degrees Celsius (800 degrees Fahrenheit) and drop to -180 degrees Celsius (-290 degrees Fahrenheit) at night. It is unlikely life (as we know it) could survive on this planet. 10. Standing on on Mercury's surface at its closest point to the sun, the sun would appear more than three times larger than it does on Earth.
1. VENUSVenus is only a little smaller than Earth.
2. Venus is the second closest planet to the sun at a distance of about 108 million km (67 million miles) or 0.72 AU. 3. One day on Venus lasts as long as 243 Earth days (the time it takes for Venus to rotate or spin once). Venus makes a complete orbit around the sun (a year in Venusian time) in 225 Earth days. 4. Venus is a rocky planet, also known as a terrestrial planet. Venus' solid surface is a cratered and volcanic landscape. 5. Venus' thick and toxic atmosphere is made up mostly of carbon dioxide (CO2) and nitrogen (N2), with clouds of sulfuric acid (H2SO4) droplets. 6. Venus has no moons.
7. There are no rings around Venus.
8. More than 40 spacecraft have explored Venus. The Magellan mission in the early 1990s mapped 98 percent of the planet's surface. 9. No evidence for life has been found on Venus. The planet's extreme high temperatures of almost 480 degrees Celsius (900 degrees Fahrenheit) make it seem an unlikely...
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