Beautiful and mysterious, peaceful and serene, the moon is the brightest object in the night sky. Jupiter and Saturn have more than sixty moons each. Neptune has thirteen moons. Even Mars has two moons. But the Earth, our planet, only has one moon, our nearest neighbor in space. Even though the moon is close to us when compared to other planets, it is still very, very far away. The moon is about 239 thousand miles or 384 thousand kilometers away. You would have to travel all the way around the Earth nine and a half times to go the same distance as the space between the Earth and the Moon. The moon is much smaller than the Earth. Ifthe Earth was hollow, about fifty moons could fit inside. Because it is so much smaller than the Earth, the moon's gravity is much weaker. This means that if you were to visit the moon, you would weigh much less than you do on earth, only about 1/6th of your current weight. That means that if a giraffe was on...
The planet Mercury is named after the messenger of the Roman gods, because even the ancients could see how swift and fleeting it is in the sky. But it wasn't until recently that scientists began unraveling Mercury's many mysteries. Mercury is the smallest planet in our solar system. It's diameter currently measures just over 3,000 miles, about the size of the continental United States.
The planet Mercury is named after the messenger of the Roman gods, because
The planet Mercury is named after the messenger of the Roman gods, because
Like Earth, Mercury is a terrestrial planet with three main layers, acore, a mantle, and a crust. Only Mercury's crusthas no tectonic plates. Also, its iron core is enormous by comparison, making up 85% of its radius, while Earth's inner and outer core account for just 55%. Because of the core's exceptional size, it's had a surprising influence on Mercury's overall size,by causing it to shrink.
The hot iron core has slowly cooled and contracted over the planet's 4.5 billion years. In doing so, it pulled Mercury's surface inward, and has caused theplanet to shrink radially by more than four miles. This shrinking planet is alsothe planet closest to the sun, orbiting our solar system's star at an average distance of roughly 36 million miles.
Such proximity affects Mercury's atmosphere, or rather, the lack of one. It only has a very thin exosphere, which is traditionally the outermost layer of a planet's atmosphere. This exosphere is made of oxygen, sodium, hydrogen, helium, and potassium, all whipped up from the planet's surface by solar winds. The lack of atmosphere andclose proximity to the sun also makes Mercury a planet of extremes.
The surface temperature can climb to 800 degrees Fahrenheit during the day time, and fall to 290 degrees below zero at night. Mercury's proximity tothe sun is also the reason behind it's ago old reputation of being swift and fleeting. The sun's gravity pulls harder on Mercury than any other planet,and like all planets, Mercury travels in an elliptical orbit, slowing down when it's away from the sun, and accelerating as it draws closer. Clocking in at an average speed of over 100,000 miles per hour, Mercury slings around the sun in just 88 days. From Earth, Mercury is difficult to observe because it's fleeting and so close to the sun. And so far, it's only been visited by two spacecraft, NASA's Mariner 10 and Messenger.
Those missions gave us much of what we know today, but future ventures are in the works with high hopes of revealing more of Mercury's secrets.
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