Equator

-

Equator, in astronomy, the great circle in which the plane of the equator of the earth intersects the celestial sphere. The celestial equator is the line from which the declination of stars and planets is measured. See Ecliptic.

Comments

Post a Comment

Popular posts from this blog

Solar System

-
Image
Solar System, the Sun and everything that orbits the Sun, including the nine planets and their satellites ; the asteroids and comets ; and interplanetary dust and gas. The term may also refer to a group of celestial bodies orbiting another star (see Extrasolar Planets ). In this article, solar system refers to the system that includes Earth and the Sun. The dimensions of the solar system are specified in terms of the mean distance from Earth to the Sun, called the astronomical unit (AU). One AU is 150 million km (about 93 million mi). The most distant known planet, Pluto , orbits about 39 AU from the Sun. Estimates for the boundary where the Sun’s magnetic field ends and interstellar space begins—called the heliopause—range from 86 to 100 AU. The most distant known planetoid orbiting the Sun is Sedna, whose discovery was reported in March 2004. A planetoid is an object that is too small to be a planet. At the farthest point in its orbit, Sedna is about 900 AU from the Sun. Com
Read more

Mirfak

-
Mirfak, sometimes spelled Mirphak or Marfak, brightest star in the constellation Perseus, the Warrior. The star is also known as Algenib and is designated Alpha Persei. The name Mirfak is derived from the Arabic phrase Mirfaq al Thurayya, the “Elbow Nearest the Many Little Ones.” This refers to Mirfak’s position in Perseus near the Pleiades star cluster. Mirfak lies near the north celestial pole, a point in the sky about which the stars in the northern hemisphere appear to rotate. This appearance is actually due to the rotation of the earth. Observers who are north of latitude 40° north can see Mirfak all night long throughout the year, circling the north celestial pole. For this reason, Mirfak is called a north circumpolar star. Observers in the southern hemisphere can see Mirfak low in the northern sky from September through November. Stars that are visible to the unaided eye, such as Mirfak, belong to the earth’s home galaxy, the Milky Way , and tend to be very bright or relativel
Read more

Earth

-
Image
Earth (planet), one of nine planets in the solar system , the only planet known to harbor life, and the “home” of human beings. From space Earth resembles a big blue marble with swirling white clouds floating above blue oceans. About 71 percent of Earth’s surface is covered by water, which is essential to life. The rest is land, mostly in the form of continents that rise above the oceans. Earth’s surface is surrounded by a layer of gases known as the atmosphere , which extends upward from the surface, slowly thinning out into space. Below the surface is a hot interior of rocky material and two core layers composed of the metals nickel and iron in solid and liquid form. Unlike the other planets, Earth has a unique set of characteristics ideally suited to supporting life as we know it. It is neither too hot, like Mercury , the closest planet to the Sun, nor too cold, like distant Mars and the even more distant outer planets— Jupiter , Saturn , Uranus , Neptune , and tiny Pluto . Earth’s
Read more