Astronomy Test- Earth and Environmental Science – Flashcards
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Lunar Eclipse
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An eclipse in which the moon appears darkened as it passes into the earth's shadow. This happens on a full moon.
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Solar Eclipse
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An eclipse in which the sun is obscured by the moon. This happens on a new moon.
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Penumbra
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The shadow cast by the earth or moon over an area experiencing a partial eclipse.
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Umbra
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The dark central part of a sunspot.
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Planet
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A body that orbits the Sun, is massive enough for its own gravity to make it round.
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Solar System
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Consists of the Sun, the planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. It includes: the satellites of the planets; numerous comets, asteroids, and meteoroids; and the interplanetary medium.
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Galaxy
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The solar system is a part; the Milky Way.
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Universe
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All of space and everything in it including stars, planets, galaxies, etc.
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How was the Solar System formed?
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A cloud of gas and dust in space was disturbed, maybe by the explosion of a nearby star (called a supernova). This explosion made waves in space which squeezed the cloud of gas and dust also known as the Big Bang.
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How does the earth move?
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It moves, or revolves, around the Sun. It's path around the Sun is called its orbit. It takes one year, or 365 1/4 days, to completely orbit the Sun. As it orbits the Sun, the Moon orbits it.
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Precession
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The slow movement of the axis of a spinning body around another axis due to a torque (such as gravitational influence) acting to change the direction of the first axis. It is seen in the circle slowly traced out by the pole of a spinning gyroscope.
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Nutation
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A periodic oscillation of the earth's axis that causes the precession of the poles to follow a wavy rather than a circular path.
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Kepler's First Law
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Object at rest stays at rest. Object in motion stays in motion.
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Kepler's Second Law
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More force means more acceleration. More mass means less acceleration.
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Kepler's Third Law
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For every force there is an equal and opposite force.
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What causes earths seasons?
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The tilt of the Earth's rotational axis away or toward the sun as it travels through its year-long path around the sun.
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Why does the sun shine?
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Nuclear fusion in the core maintains both gravitational equilibrium between pressure and gravity and energy balance between thermal energy released in core and radioactive energy lost from the Sun's surface.
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The Big Bang Theory
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The leading explanation about how the universe began. At its simplest, it talks about the universe as we know it starting with a small singularity, then inflating over the next 13.8 billion years to the cosmos that we know today.
