Astronomy Test- Earth and Environmental Science
Lunar Eclipse
An eclipse in which the moon appears darkened as it passes into the earth’s shadow. This happens on a full moon.
Solar Eclipse
An eclipse in which the sun is obscured by the moon. This happens on a new moon.
Penumbra
The shadow cast by the earth or moon over an area experiencing a partial eclipse.
Umbra
The dark central part of a sunspot.
Planet
A body that orbits the Sun, is massive enough for its own gravity to make it round.
Solar System
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.
Galaxy
The solar system is a part; the Milky Way.
Universe
All of space and everything in it including stars, planets, galaxies, etc.
How was the Solar System formed?
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.
How does the earth move?
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.
Precession
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.
Nutation
A periodic oscillation of the earth’s axis that causes the precession of the poles to follow a wavy rather than a circular path.
Kepler’s First Law
Object at rest stays at rest. Object in motion stays in motion.
Kepler’s Second Law
More force means more acceleration. More mass means less acceleration.
Kepler’s Third Law
For every force there is an equal and opposite force.
What causes earths seasons?
The tilt of the Earth’s rotational axis away or toward the sun as it travels through its year-long path around the sun.
Why does the sun shine?
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.
The Big Bang Theory
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.