The Solar System

Unit Review Sheet

Facts and Definitions

Lesson 1: The Latest View of Our Solar System

• A light year is how we measure distance in space. The distance light travels in one year in a vacuum is one light year. It equals 5,878,625,373,184 miles (roughly 5.9 trillion miles).
• Orbit means the path of a celestial body or an artificial satellite as it revolves around another body.
• A planet is a large, round body that orbits a star.

Lesson 2: Our Sun

• The bright outer layer of the Sun is called the photosphere.
• Sunspots are dark markings on the Sun's surface. They look dark because they are slightly cooler than the surrounding area.
• Solar flares are explosions of energy in the Sun's atmosphere near a sunspot.
• Solar prominences are loops or clouds of gas that extend out from the Sun's surface.

Lesson 3: Earth, the Third Planet

• The axis is an imaginary line through a planet, about which the planet rotates, or turns, making day and night.
• We define the length of days/nights on other planets using our 24-hour Earth day as a standard. We also use Earth year to describe the length of other planets' orbits around the Sun in comparison to our own.
• Super-Earths are planets orbiting other stars where conditions make it possible for liquid water to exist on their surfaces.

Lesson 4: Satellites and Telescopes

• Any object, natural or man-made, that orbits around a planet, is called a satellite.
• A satellite that orbits Earth directly above the equator, making it circle the Earth only once per day, is said to be in geostationary orbit.
• A topographic map is a map often developed from satellite images having detailed information about the heights and depths of geographic features.
• Spectral analysis is a way of determining what chemicals are in a celestial body by comparing the spectral lines from different atoms and molecules.
• Reflectance curves are part of spectral analysis that help identify specific chemicals and compounds in celestial bodies by plotting how they reflect light.

Lesson 5: Meteorites and the Moon

• A meteroid is a small piece of metal or stone traveling through space. If it travels through the Earth's atmosphere, leaving a streak of light as it burns, it's called a meteor. If it hits the ground, it's called a meteorite.
• A natural satellite of any planet is called a moon. We usually capitalize Moon when talking about Earth's moon to distinguish it from the moons of other planets.
• The tidal bulge is a stretching of the Earth's oceans and atmosphere caused by the gravitational pull of the Moon. This pull creates two bulges: one on the side of Earth facing the Moon and another on the opposite side, leading to high tides in those areas.

Lesson 6: Other Terrestrial Planets

• A terrestrial planet is a class of planet made up of mostly silicate rocks. This class includes Mercury, Venus, Earth, and Mars.

Lesson 7: Gas Giants

• A gas giant is a large planet made mostly of frozen hydrogen and helium; the gas giants are Jupiter, Saturn, Uranus, and Neptune.

Lesson 8: Dwarf Planets and Asteroids

• A dwarf planet is one of a new class of small planets, including Pluto, Ceres, Haumea, Makemake, and Eris.

Lesson 9: Men on the Moon and Beyond

• The spaceflight program that first landed humans on the Moon was called the Apollo program. The Apollo 11 mission let astronauts Neil Armstrong and Buzz Aldrin walk on the surface of the Moon on July 20, 1969.
• NASA is the United States' National Aeronautics and Space Administration.
• The International Space Station is an international research facility that has been in orbit since 1998. It was assembled in orbit.

Final Project: Solar System Model and Test

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