The Earth has been described as being in the habitable zone, which is a theoretical area in a Solar System where the conditions are optimal for the existence of life
The German astronomer Simon Marius claimed to have seen the moons around the same time, but he did not publish his observations and so Galileo is given the credit for their discovery. Ganymede is the largest moon in the solar system (larger than the planet Mercury), and is the only moon known to have its own internally generated magnetic field
What Will Happen to the Earth When the Sun Dies? - NASA Spitzer Space Telescope
Watch now 02.05.09 W-5 Star-Forming Region Visit the W-5 star-forming region with 'Ask an Astronomer'! Watch now 12.22.08 Why Is the Sky Blue? In this 'Ask an Astronomer' episode, Dr. Watch now 12.09.05 Do the Stars Really Move? The answer to this 'Ask an Astronomer' question may surprise you! Watch now 10.25.05 Why Do We See Spiral Arms in Some Galaxies? 'Ask an Astronomer' explains the morphology of one of the most common types of galaxy
By understanding the natural processes and variability of this system, we can be prepared for the disasters that at times can occur and understand the conditions necessary for life to exist on any planetary system. In addition, the Air Force, recognizing the danger to humans and systems in space, supports a great deal of research in this topic area, as does the Department of Energy (at LANL) and the Department of Commerce (at NOAA)
Had the planet been 80 times larger, hydrogen fusion would have begun in the core of Jupiter, and a brown dwarf star would have been born instead of a planet
A great source of information on upcoming eclipses (and eclipses in general) is Fred Espenak's Eclipse Home Page at the NASA Goddard Space Flight Center. The reason is simple: as you move outwards away from the edge of the umbra, you will see an increasing fraction of the Sun peeking out from behind the Moon
Currently, the Earth is closest to the Sun in January, giving the northern hemisphere slightly shorter, warmer winters and longer, cooler summers than the southern hemisphere. EarthImage: NASAThe role of carbon dioxide in the ice age cycles Scientists examining ice core data have observed that levels of carbon dioxide (CO2) in the atmosphere changed almost perfectly in step with temperature during the ice age cycles
DOPPLER SHIFT A shift in an object's spectrum due to a change in the wavelength of light that occurs when an object is moving toward or away from Earth. I IMPACT CRATERS Craters which are the result of a collision between a large body, such as a planet or satellite, and a smaller body such as an asteroid or meteorite
Spacecraft are constantly increasing our understanding of the sun -- from Genesis (which collected samples of the solar wind and returned the particles to Earth) to SOHO, STEREO THEMIS, and many more, which are examining the sun's features, its interior and how it interacts with our planet. The sun is orbited by eight planets, at least five dwarf planets, tens of thousands of asteroids, and hundreds of thousands to three trillion comets and icy bodies
The outermost part of the crust is broken and jumbled due to all the large impacts it has received, a shattered zone that gives way to intact material below a depth of about 6 miles (9.6 km). The average composition of the lunar surface by weight is roughly 43 percent oxygen, 20 percent silicon, 19 percent magnesium, 10 percent iron, 3 percent calcium, 3 percent aluminum, 0.42 percent chromium, 0.18 percent titanium and 0.12 percent manganese
The highly rarefied region above the chromosphere, called the corona, extends millions of kilometers into space but is visible only during a total solar eclipse (left). (Exactly which bodies should be classified as planets and which as "smaller objects" has been the source of some controversy, but in the end it is really only a matter of definition
The moon may have once been a part of the Earth; it may have been broken off the Earth during a catastrophic collision of a huge body with the Earth billions of years ago. The atmosphere was formed by planetary degassing, a process in which gases like carbon dioxide, water vapor, sulphur dioxide and nitrogen were released from the interior of the Earth from volcanoes and other processes
The element helium was discovered by Jules Janssen during the total solar eclipse of 1868 when he detected a new line in the solar absorption spectrum; Norman Lockyer suggested the name helium. Although the nuclear output of the sun is not entirely consistent, each second the Sun converts about 600,000,000 tons of hydrogen nuclei into helium nuclei
These kinks and twists in the magnetic field develop because the sun spins more rapidly at the equator than at the higher latitudes and because the inner parts of the sun rotate more quickly than the surface. It has imaged the structure of sunspots below the surface, measured the acceleration of the solar wind, discovered coronal waves and solar tornadoes, found more than 1,000 comets, and revolutionized our ability to forecast space weather
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