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Drake Equation Is there a way to estimate the number of technologically advanced civilizations that might exist in our Galaxy? While working at the National Radio Astronomy Observatory in Green Bank, West Virginia, Dr. Frank Drake conceived a means to mathematically estimate the number of worlds that might harbor beings with technology sufficient to communicate across the vast gulfs of interstellar space. The Drake Equation, as it came to be known, was formulated in 1961 and is generally accepted by the scientific community.
Where...
Dr. Frank Drake's own current solution to the Drake Equation estimates 10,000 communicative civilizations in the Milky Way.
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Planetary Facts & Figures |
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Planet Surface
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Mercury, the planet closest to the Sun, has almost no atmosphere and its dusty surface of craters resembles the Moon. The planet was named for the Roman god Mercury, a winged messenger, because it travels through the sky quickly. In fact, it travels around the Sun faster than any other planet. Mercury is difficult to see from Earth because of the glare from the sun. Nicolaus Copernicus, for all his years of research and observation, never once was able to see Mercury. | |||||||||||||||||||||||
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Global View
Volcanoes |
Venus is often called Earth's twin because the two planets are close in size but that's the only similarity. The thick clouds that cover Venus create a greenhouse effect that keeps it sizzling at 864°F. Venus, named after the Roman goddess of love and beauty, is also known as the “morning star” and “evening star” since it is visible at these times to the unaided eye. Venus appears as a bright, white disk from Earth. | |||||||||||||||||||||||
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Earth is not perfectly round as it bulges at the equator and is flatter at the poles. From space the planet looks blue with white swirls, created by water and clouds. Only planet known to have life. | |||||||||||||||||||||||
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Global View
Largest volcano in Solar System |
Because of its blood-red color (which comes from iron-rich dust), this planet was named for Mars, the Roman god of war. Mars is the fourth planet from the Sun, situated between Earth and Jupiter. Three-quarters red, Mars also has dark blotches on it and white areas at the poles (which are polar ice caps made of frozen water/carbon dioxide.) | |||||||||||||||||||||||
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Gaspra
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Asteroids are small bodies that are believed to be left over from the beginning of the solar system 4.6 billion years ago. They are rocky objects with round or irregular shapes up to several hundred km across, but most are much smaller. More than 100,000 asteroids lie in a belt between Mars and Jupiter. These asteroids lie in a location in the solar system where there seems to be a jump in the spacing between the planets. Scientists believe the Asteroid Belt is either an unformed planet or a planet that was broken apart due to the gravity of Jupiter or by a large impact. | |||||||||||||||||||||||
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Jupiter & Ganymede
Io, in eclipse |
Jupiter, the largest planet in our solar system, was named for the most important Roman god because of its size. About 1,300 Earths would fit into the planet. Viewed through a large telescope, Jupiter is stunningly colorful—it is a disk covered with bands of blue, brown, pink, red, orange and yellow. Its most distinguishing feature is “the Great Red Spot,” an intense windstorm larger in size than the Earth, which has continued for centuries without any signs of dying down. | |||||||||||||||||||||||
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Cassini spacecraft during flyby of Saturn |
Saturn, the second-largest planet, has majestic rings surrounding the planet. Named for the Roman god of farming, Saturn was the farthest planet known by the ancients. Saturn's rings are flat and lie inside one another. They are made of billions of ice particles and rock. Saturn is of such low density that if you could place the planet in a bathtub, (imagine the size!), it would float! | |||||||||||||||||||||||
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Uranus is a greenish-blue planet, twice as far from the Sun as its neighbor Saturn. Uranus wasn't discovered until 1781. It's discoverer, William Herschel, named it Georgium Sidus (the Georgian star) after the English king, George III. Later its name was changed to Uranus, after an ancient Greek sky god, since all the other planets had been named after Roman and Greek gods. | |||||||||||||||||||||||
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Global View showing "Great Blue Spot." This spot has disappeared and reappeared indicating that storms form and dissipate similar to weather systems on Earth. |
Neptune, named for an ancient Roman sea god, is a stormy blue planet about 30 times farther from the Sun than Earth. Neptune was discovered when astronomers realized that something was exerting a gravitational pull on Uranus and that it was possible that an unknown planet might be responsible. Through mathematical calculations, astronomers determined there was indeed an undiscovered planet out in space—a year before it was actually seen for the first time through a telescope (in 1846). | |||||||||||||||||||||||
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Pluto & Charon
Pluto & Charon as seen by the Hubble telescope |
Pluto, named after the Roman and Greek god of the underworld, is the coldest, smallest and outermost body in our solar system. Pluto has been demoted as a full planet and is now referred to as a "plutonian" or "dwarf planet." Pluto and its moon, Charon, are called "double planets" because Charon is so large it seems less of a moon than another planet. Pluto was predicted to exist in 1905 and discovered in 1930. It is the only solar system body that has not yet been studied closely by a space probe. This will change with the New Horizons Mission which will reach Pluto in July of 2015. During each revolution around the sun, Pluto passes inside Neptune's orbit for 20 years, making Neptune the outermost planet for that time. Pluto passed inside Neptune's orbit in 1979 and remained there until 1999. It will not return to that position until 2227. | |||||||||||||||||||||||
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