Download Astronomy Objective 1 1. An asteroid is a small, rocky object that

Astronomy Objective 1
1. An asteroid is a small, rocky object that orbits the sun; most are located
in a band between the orbits of Mars and Jupiter.
2. An astronomical unit (AU) is the average distance between the Earth and
the sun; approximately 150 million kilometers (93 million miles).
3. Astronomy is the scientific study of the universe.
4. The big bang theory is the theory that all matter and energy in the
universe was compressed into an extremely small volume that 13 billion to
15 billion years ago exploded and began expanding in all directions.
5. A black hole is an object so massive and dense that even light cannot
escape its gravity.
6. A comet is a small body of ice, rock, and cosmic dust that follows an
elliptical orbit around the sun that gives off gases and dust in the form of a
tail as it passes close to the sun.
7. A constellation is one of 88 regions into which the sky is divided in order
to describe locations of celestial objects; a group of stars organized in a
recognizable pattern.
8. A galaxy is a collection of stars, dust, and gas bound together by gravity.
9. A light year is the distance light travels in one year; about 9.46 trillion
kilometers (6 trillion miles).
10. A lunar eclipse is the passing of the moon through the Earth’s shadow at
full moon.
11. A meteor is a bright streak of light that results when a meteoroid burns
up in Earth’s atmosphere.
12. A meteorite is a meteoroid or any part of a meteoroid that is left when a
meteoroid hits the Earth.
13. A meteoroid is a relatively small, rocky body that travels through space.
14. A moon is a celestial body that revolves around a body that is larger in
mass; a natural satellite.
15. A nebula is a large cloud of gas and dust in interstellar space; a region in
space where stars are born.
16. A nova is a star that suddenly becomes brighter.
17. uclear fusion is a process by which nuclei of small atoms combine to
form new, more massive nuclei; the process releases energy.
18. A planet is a celestial body that orbits the sun, is round because of its
own gravity, and has cleared the neighborhood around its orbital path.
19. Revolution is the motion of a body that travels around another body in
space; one complete trip along an orbit.
20. Rotation is the spin of a body on its axis.
21. A solar eclipse is the passing of the moon between Earth and the sun;
during this the shadow of the moon falls on the Earth.
22. A solar flare is an explosive release of energy that comes from the sun
and that is associated with magnetic disturbances on the sun’s surface.
23. The solar system is the sun and all of the planets and other bodies that
travel around it.
24. A star is a large celestial body that is composed of gas and that emits
light.
25. The solar wind is electrons and electrically charged particles (ions)
which flow outward from the sun to the rest of the solar system.
26. A sunspot is a dark area of the photosphere of the sun that is cooler than
the surrounding areas and that has a strong magnetic field.
27. A telescope is an instrument that collects electromagnetic radiation from
the sky and concentrates it for better observation.
28. The universe is all existing matter, energy, and space.