| Alpha Centauri |
a double star in the constellation Centaurus, the closest star to the solar system, having a combined magnitude of -0.3. |
| Aurora |
(l.c.) bands or streamers of light that appear in the sky at night in areas around the magnetic poles, caused by solar particles striking atoms in the outer part of the earth's atmosphere. (See aurora australis, aurora borealis.) [1/3 definitions] |
| chondrite |
a stony meteorite that contains chondrules, formed from materials present in the early solar system . |
| cosmic ray |
high energy radiation, consisting primarily of high-energy protons and alpha particles, that primarily originates from outside the solar system. Upon collision with earth's atmosphere, secondary particles can be produced that sometimes reach the earth's surface. |
| earth |
(often capitalized) the fifth largest planet in our solar system and the third in distance from the sun. [1/4 definitions] |
| Enceladus |
one of several moons of the planet Saturn, having more reflective brightness than any other body in the solar system. |
| geocentric |
designating the earth as the center, as of the universe or solar system. [1/2 definitions] |
| greenhouse effect |
the warming trend on the surface and in the lower atmosphere of a planet, held by scientists to occur when solar radiation is trapped, as by gas emissions from the planet. |
| Greenwich time |
the solar time that is determined at the prime meridian through Greenwich, England, and that is used to calculate and regulate time throughout most of the world; Greenwich mean time. |
| insolation |
solar radiation received, or the rate of solar radiation per unit of surface or area. [1/3 definitions] |
| intercalary |
of a day or month, inserted into the calendar to bring the calendar year into correspondence with the solar year. [1/2 definitions] |
| Jupiter |
the largest planet in the solar system and fifth in distance from the sun. Jupiter has sixteen moons and is more than one thousand times larger than Earth. [1/2 definitions] |
| langley |
a unit of illumination used for measuring solar radiation, equal to one small calorie per square centimeter. |
| magnetic storm |
a temporary widespread disturbance of the earth's magnetic field, caused by unusual solar activity. |
| Mars |
the seventh largest planet in the solar system and fourth in distance from the sun. Mars is known as "the red planet" because of its unusual color. [1/2 definitions] |
| mercury |
(capitalized) the planet of the solar system that is nearest to the sun. Mercury is the second smallest planet. [1/3 definitions] |
| Milky Way |
the galaxy that contains the earth, the sun, and the solar system. It can be seen in the night sky as a long, cloudy group of stars. |
| nebular hypothesis |
a theory stating that the solar system was once a nebula that cooled and condensed to form the sun and planets. |
| Neptune |
the fourth largest planet in the solar system and eighth in distance from the sun. [1/2 definitions] |
| nonsolar |
combined form of solar. |
| orrery |
a model of bodies in the solar system that can show their relative positions and motions by means of simple mechanical adjustments. |