Sun Characteristics and Solar System

Sun Characteristics

• Sunspots: Darker markings on the sun's surface, lasting 1-100 days and usually appearing in groups.
• The sun's radius is 109 times the radius of the Earth, with a density of about one fourth of Earth's due to its gaseous composition.
• The sun's core is composed of plasma.

Sun Surface Activity

• Spicules: Jets of gas ejected from the sun's surface, typically found along the outline of a supergranule.
• Solar prominence: A loop of gas rising from the sun and then falling back.

Solar Flares and Solar Wind

• Solar flare: A huge burst of particles and energy shot out into space at speeds greater than the escape velocity.
• Solar wind: Streams of particles and energy traveling through space, created by solar flares.

Motion of the Sun

• The sun rotates on its axis about once per month, as discovered by Galileo by observing the motion of sunspots.
• The sun's surface rotates differentially, with faster rotation near the equator and slower rotation near the poles.

Planetary Motion

• All planets have nearly circular orbits around the sun.
• All planets orbit in the same direction.
• All planets, except Venus, rotate on their axis in the same direction.
• The period of orbit increases with the planet's distance from the sun.
• The distances between the planets become greater as you move outward from the sun.