Which planets have the most moons? Are they large or small planets?
The larger planets have a stronger gravitational pull, so they often have many satellites, or moons. These larger planets can “capture” or pull moons into their gravitational fields more easily because objects (such as moons) move more slowly in space.
Which planet has a “day” that is longer than its “year”?
Venus rotates very slowly on its axis: one day is as long as 243 days on Earth! Yet Venus completes an orbit around the sun in only 225 days.
Which planets have the fastest orbital speeds? Are the faster planets near the sun or far from the sun?
The planets closer to the sun move through space faster.
What else is out there?
Beyond Neptune there is a ring of thousands of small bodies orbiting the sun. This
FunFacts
Pluto was discovered in 1930. For 76 years it was considered a planet. In 2006, Pluto was reclassified as a dwarf planet. Since its discovery, Pluto has completed only 31% of one revolution around the sun. By the year 2178, it will have completed one revolution (or one Plutonian year).
Jupiter spins the fasteston its axis. Its day lasts less than 10 hours. It also spins so fast that the round planet has a flattened appearance.
In 1543, the Polish astronomer and priest Nicolaus Copernicus noted that Earth revolved around the sun. Before then, people believed that the sun revolved around Earth.
The sun is very large compared to the planets. However, compared to other stars, the sun is an
UsingtheStarDome
Here’s a second way to explore space: create your own classroom planetarium! The star dome converts the solar system model into a planetarium projector.
1.Remove the top half of the sun sphere. Put the star dome in its place. Make sure the tab on the edge of the star dome fits into the notch on the lower half of the sun sphere.
2.The projected image will look best in a darkened room. If possible, turn off the lights and close the shades.
3.Switch on the light at the base of the tower. Stars, constellation names, and constellation outlines will be projected onto the walls and ceiling of the room. The farther light travels before hitting a surface, the bigger the image will appear. Moving the tower closer to and further from the walls or ceiling will alter the image. To get the best image, experiment with different distances.
StarDomeClassroomActivities
Constellations are clustersof stars whose patterns resembleshapes and figures. Breaking the 1,000 to 1,500 stars visible on a dark night into constellations helps people easily find and rememberthe names and locations of stars. For thousands of years, different cultures have divided the night sky into differentconstellations.They used the stars to help them navigate, to plan when to plant crops, and for religious purposes. The Greeks and Romans named their constellations after the gods and heroes in their mythology. In 1929 the International Astronomical Union divided the stars into 88 official constellations that are used by astronomers today. Most of these constellations come from the Greek and Roman view of the sky. The next page lists constellations that are on this model’s star dome. As your class observes this stellar display, try some of the activities provided. Note: Southern Hemisphere constellations are not included in this list.
