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Astronomy Reference Libraries

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Neptune
2004-10-19 04:45:41

Planet Neptune -- Neptune is the eighth planet from the sun. It is a gas giant. Orbiting so far from the sun, Neptune receives very little heat. Its 'surface' temperature is -218 degrees Celsius (below zero). However, the planet seems to have an internal source of heat. It is thought that this may be leftover heat generated by infalling matter during the planet's birth, now slowly...

Uranus
2004-10-19 04:45:41

Uranus -- Uranus is the seventh planet from the sun. It is a gas giant. Physical characteristics Uranus is composed primarily of rock and various ices, with only about 15% hydrogen and a little helium (in contrast to Jupiter and Saturn which are mostly hydrogen). Uranus (and Neptune) are in many ways similar to the cores of Jupiter and Saturn minus the massive liquid metallic hydrogen...

Telesto Saturn Moon
2004-10-19 04:45:41

Telesto is a small Trojan moon of the sixth planet from the sun, Saturn. Telesto, which was discovered in 1980 by Smith, Reitsema, Larson and Fountain, is one of around 200 natural satellites in Saturnian orbit. It is one of only 62 moons that have a secure orbit, and only one of 53 named moons orbiting the ringed planet. Telesto was officially designated S/1980 S 13 and was officially named...

Saturn
2004-10-19 04:45:41

The Planet Saturn -- in astronomy, 6th planet from the sun. Astronomical and Physical Characteristics of Saturn Saturn's orbit lies between those of Jupiter and Uranus; its mean distance from the sun is c.886 million mi (1.43 billion km), almost twice that of Jupiter, and its period of revolution is about 291/2 years. Saturn appears in the sky as a yellow, starlike object of the first...

Jupiter
2004-10-19 04:45:40

Jupiter -- in astronomy, fifth planet from the sun and largest planet of the solar system. Astronomical and Physical Characteristics Jupiter's orbit lies beyond the asteroid belt at a mean distance of 483.6 million mi (778.3 million km) from the sun; its period of revolution is 11.86 years. In order from the sun it is the first of the Jovian planetsJupiter, Saturn, Uranus, and...

The Sun
2004-10-19 04:45:40

The Sun -- intensely hot, self-luminous body of gases at the center of the solar system. Its gravitational attraction maintains the planets, comets, and other bodies of the solar system in their orbits. The sun is actually a star of about medium size; it appears larger than the other stars because of its relative nearness to the earth. The earth's distance from the sun varies from 91,377,000...

Venus
2004-10-19 04:45:40

The Planet Venus is the second planet from the sun. It is often called the evening star or morning star and is brighter than any object in the sky except the sun and the moon. Because its orbit lies between the sun and the orbit of the earth, Venus passes through phases like those of the moon, varying from a large bright crescent when the planet is near inferior conjunction (nearest the...

Mercury
2004-10-19 04:45:40

The Planet Mercury -- in astronomy, nearest planet to the sun, at a mean distance of 36 million mi (58 million km); its period of revolution is 88 days. Mercury passes through phases similar to those of the moon as it completes each revolution about the sun, although the visible disk varies in size with respect to its distance from the earth. Because its greatest elongation is 28, it is seen...

Mars
2004-10-19 04:45:40

The Planet Mars -- in astronomy, 4th planet from the sun, with an orbit next in order beyond that of the earth. Physical Characteristics Mars has a striking red appearance, and in its most favorable position for viewing, when it is opposite the sun, it is twice as bright as Sirius, the brightest star. Mars has a diameter of 4,200 mi (6,800 km), just over half the diameter of the...

Earth
2004-10-19 04:45:40

Earth -- in geology and astronomy, fifth largest planet of the solar system and the only planet definitely known to support life. Gravitational forces have molded the earth, like all celestial bodies, into a spherical shape. However, the earth is not an exact sphere, being slightly flattened at the poles and bulging at the equator. The equatorial diameter is c.7,926 mi (12,760 km) and the...

Word of the Day
endocarp
  • The hard inner (usually woody) layer of the pericarp of some fruits (as peaches or plums or cherries or olives) that contains the seed.
This word comes from the Greek 'endon,' in, within, plus the Greek 'kardia,' heart.
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