EARTH & ENVIRONMENTAL SCIENCE | Unit: Astronomy

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Astronomy
The science that studies the universe. It includes the observation and interpretation of celestial bodies and phenomena.
Nebula
Rotating clouds of interstellar gas or dust composed of hydrogen and helium
Terrestrial Planets
Planets that are small and rocky– Mercury, Venus, Earth, and Mars
Jovian Planets
The huge gas giants–Jupiter, Saturn, Uranus, and Neptune
Atmosphere of the Jovian Planets
Very thick atmospheres of hydrogen, helium, methane, and ammonia
Atmosphere of Terrestrial Planets
Have meager atmospheres at best
Johannes Kepler
German astronomer and mathematician. 1571 to 1630 who is famous for his laws of planetary motion
Three Laws of Planetary Motion
1. Orbits of the planets are elliptical
2. Planets revolve around the sun at varying speed
3. There is a proportional relationship between a planet’s orbital period and it’s distance to the sun
Ellipse
An oval – shaped path
Astronomical Unit (AU)
The average distance between Earth and the sun; it’s about 150 million kilometers
Rotation
The turning, or spinning, of a body on its axis
Mean Solar Day
The time interval from one noon to the next, about 24 hours . The clocks we use for civil timekeeping are based on this motion.
Sidereal Day
It takes time for Earth to make one complete rotation (360) with respect to a star other than the sun–23 hours, 56 minutes, and 4 seconds
Revolution
The motion of a body, such as a planet or moon, along a path around some point in space.
Perihelion
The time in January when Earth is closest to the sun.
Aphelion
The time in July when Earth is farthest from the sun
Solstice
Farthest north and south that the sun appears in the sky
Equinoxes
When the sun appears directly over the equator (equal day & night)
Barycenter
The balance between the masses of the planets as they orbit. Causes the sun to wobble-it is not stationary in the solar system.
The Moon
1/4 the diameter of the Earth.
Perigee
The point at which the moon is closest to the Earth
Apogee
The point at which the moon is farthest from the Earth.
Tides
The alternating pattern of rising and falling sea level with respect to land.
Photosphere
The region of the sun that radiates energy to space, or the visible surface of the sun
Chromosphere
The first layer of the solar atmosphere found directly above the photosphere.
Corona
The outer, weak layer of the solar atmosphere.
Nuclear fusion
The way that the sun produces energy. It is when hydrogen turns to helium in the suns core and generates the energy.
Fission
When an atom splits into two parts, either through natural decay or when instigated within a lab, it releases energy.
Solar Energy
Energy ( light or heat) from the sun
Electromagnetic Waves
The sun emits light and heat as well as the ultraviolet rays. These forms of energy are only part of a large array of energy called the electromagnetic spectrum.
Precession
The slow top-like wobbling of the spinning of the earth
Nutation
A small, periodic oscillation of the earth’s axis which slightly varies or nods the earths precessional motion
Nebular Hypothesis
The theory that the solar and stellar systems were developed from a primeval nebula
Categories: Astronomy