planets of the solar system

orbits and rotations

Distances in the solar system are often measured in astronomical units (AU). One astronomical unit is defined as the distance from Earth to the Sun. 1 AU equals about 150 million km, or 93 million miles. Table 1.2 shows the distances to the planets (the average radius of orbits) in AU. The table also shows how long it takes each planet to spin on its axis (the length of a day) and how long it takes each planet to complete an orbit (the length of a year); in particular, notice how slowly Venus rotates relative to Earth. Planet Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Average Distance from Sun (AU) 0.39 AU 0.72 1.00 1.52 5.20 9.54 19.22 30.06 Length of Day (In Earth Days) 56.84 days 243.02 1.00 1.03 0.41 0.43 0.72 0.67 Length of Year (In Earth Years) 0.24 years 0.62 1.00 1.88 11.86 29.46 84.01 164.8 Click image to the left or use the URL below. URL:

eight planets

Since the time of Copernicus, Kepler, and Galileo, we have learned a lot more about our solar system. Astronomers have discovered two more planets (Uranus and Neptune), five dwarf planets (Ceres, Pluto, Makemake, Haumea, and Eris), more than 150 moons, and many, many asteroids and other small objects. Although the Sun is just an average star compared to other stars, it is by far the largest object in the solar system. The Sun is more than 500 times the mass of everything else in the solar system combined! Table 1.1 gives data on the sizes of the Sun and planets relative to Earth. Object Mass (Relative to Earth) Sun Mercury Venus Earth 333,000 Earths mass 0.06 Earths mass 0.82 Earths mass 1.00 Earths mass Diameter of Planet (Relative to Earth) 109.2 Earths diameter 0.39 Earths diameter 0.95 Earths diameter 1.00 Earths diameter Object Mass (Relative to Earth) Mars Jupiter Saturn Uranus Neptune 0.11 Earths mass 317.8 Earths mass 95.2 Earths mass 14.6 Earths mass 17.2 Earths mass Diameter of Planet (Relative to Earth) 0.53 Earths diameter 11.21 Earths diameter 9.41 Earths diameter 3.98 Earths diameter 3.81 Earths diameter

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which of these is a dwarf planet?

a) jupiter

b) uranus

-->  c) pluto

d) venus

through his telescope, galileo could see all the planets of the solar system.

a) true

-->  b) false

the sun is _ more the mass of the entire solar system combined.

a) 10 times

b) 20 times

c) 200 times

-->  d) 500 times

distance in the solar system is measured by ___.

a) miles

b) kilometers

-->  c) astronomical units

d) light years

the sun is _______ million miles from earth.

-->  a) 93

b) 73

c) 53

d) 33

on venus a day is equal to 243 earth days. what does this mean?

a) the length of a planets day is inversely related to its distance from the sun.

b) the length of a planets day is directly related to its distance from the sun.

-->  c) venus takes 243 earth days to rotate once on its axis.

d) venus takes 243 earth days to orbit the sun once.

one astronomical unit is 93 million miles.

-->  a) true

b) false

on which planet would your weight be closest to your weight on earth?

a) mercury

-->  b) venus

c) mars

d) jupiter

how is ceres different from the other four dwarf planets?

a) ceres is nearly as large as mercury; the others are much smaller.

-->  b) ceres orbits near jupiter; the others orbit beyond neptune.

c) ceres has microbial life, but life hasnt been found on the others yet.

d) all of these.

about how many times has mercury been around the sun in the time it has taken earth to go around ten times?

a) once

b) 2.5-times

c) 4-times

-->  d) 40-times

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