Astronomy Terms

Astronomy Terms

Astronomical Unit

the mean distance between the Earth and the Sun.

The means distance

•  the arithmetic mean of the greatest and least distances of a planet from the sun, used in stating the size of an orbit; the semimajor axis.

• Distance from point a to b.

Comets

Small balls of frozen gas and solids that take very elliptical paths around the Sun.

Aphelion

• The point in the orbit of a planet or comet when it is the farthest from the Sun.

• This usually happens between July 3rd-July 4th.

Perihelion- the point in the orbit of a planet or comet when it is at its nearest point to the Sun.

Eclipse-an obscuring of the light, usually in relation to the Sun or the Moon.

Geocentric – the idea that the planets and the Sun revolve around the Earth.

Geocentric Theory Creator

• The Danish astronomer Tycho Brahe (1546-1601), a brilliant experimental scientist whose measurements of the positions of the stars and planets surpassed any that were made prior to the invention of the telescope.

• proposed a model that attempted to serve as a compromise between the geocentric explanation and the Copernican theory.

Heleocentric

The idea that the planets, including the Earth, revolve around the Sun.

Heliocentric Theory Creator

• Galileo Galilei

  Because he advanced the heliocentric theory Galileo was forced to recant Copernicanism and was put under house arrest for the last few years of his life. 

• Saw the moons of Jupiter and the mountains on the Moon.

• Calculated the law of free fall on the basis of experiment.

• Invented the microscope.

Sunspot

• Any relatively cool or dark spot on the Sun.

• Sunspots are formed continuously as the Sun's magnetic field actively moves through the Sun.

• They can last days or week.

Supernova – a rare event involving the explosion of most of the material in a star.

Multiple Choice

What theory is the idea that the planets and sun revolve around the earth?

• Heliocentric theory

• Geocentric theory

Multiple Choice

The Aphelion is the point in the orbit of a planet or comet when it is at its nearest point to the Sun.

• True

• False

Copernicus Theory Creator

• Nicolaus Copernicus

• Hypothesized a heliocentric system, that the planets orbit around the Sun; that Earth is a planet which, besides orbiting the Sun annually, also turns once daily on its own axis; and that very slow changes in the direction of this axis account for the precession of the equinoxes.

•  Correctly described the Sun as having a central position relative to Earth and other planets.