What percentage of the solar system's total mass does the Sun contain?

About 50% About 75% About 99.8% About 100% — the planets have no mass

What keeps the planets in orbit around the Sun instead of flying off into space?

Solar wind pushes planets along their paths The Sun's gravity constantly pulls planets inward, curving their path into an orbit Planets are attached to invisible tracks in space Magnetism from the Sun holds planets in place

What shape are planetary orbits?

Perfect circles Squares Spirals Ellipses (slightly flattened circles)

Which scientist discovered that planets orbit the Sun in ellipses?

Galileo Galilei Isaac Newton Johannes Kepler Nicolaus Copernicus

Which planet moves the fastest in its orbit around the Sun?

Earth, because it supports life Jupiter, because it is the largest Neptune, because it is at the edge of the solar system Mercury, at about 47 km/s

Why does a planet closer to the Sun orbit faster than one farther away?

Inner planets are lighter and therefore move faster The Sun pushes inner planets harder with its light The Sun's gravity is stronger at closer distances, requiring the planet to move faster to maintain a stable orbit Inner planets have shorter orbits and simply finish sooner

How long does the Sun take to rotate once at its equator?

About 24 hours About 25 days About 1 year The Sun does not rotate

What is differential rotation of the Sun?

The Sun rotates in a different direction depending on the season The Sun's equator rotates faster (about 25 days) than its poles (about 35 days) because the Sun is plasma, not a solid The Sun sometimes rotates forward and sometimes backward The Sun's rotation speed changes every year

What is the ecliptic plane?

The path the Sun travels through the Milky Way galaxy The flat plane in which all planets orbit the Sun The midpoint between the Sun and the nearest star The equator of the Sun

What would happen to a planet if the Sun's gravity suddenly disappeared?

The planet would slowly spiral into where the Sun was The planet would stop moving The planet would fly off in a straight line into space The planet would orbit another planet instead

Neptune, the farthest planet, orbits the Sun at about 5.4 km/s. Mercury orbits at about 47 km/s. What does this tell us?

Neptune is moving too slowly and will eventually fall into the Sun Mercury is moving too fast and will leave the solar system Planets closer to the Sun move much faster in their orbits than planets farther away All planets should orbit at the same speed