Page 19 - (DK) Eyewitness - Mars

Average orbital speed of Venus: Perihelion of Mercury: Perihelion of Venus: 66.8 million
21.8 miles/sec (35 km/sec) Mercury 28.6 million miles miles (107.5 million km)
Average orbital speed of Mercury: (46 million km) Perihelion of Earth:
29.7 miles/sec (47.9 km/sec)
91.4 million miles
Average orbital speed of Earth: (147.1 million km) Perihelion of Pluto:
18.5 miles/sec (29.8 km/sec) Perihelion 2,755.8 million miles
of Mars: (4,435 million km)
Average orbital speed 128.4 0million
of Mars: 15 miles/sec miles (206.6
(24.1 km/sec) million km)
Earth
Venus
Mars Sun
Aphelion of Mercury:
Asteroid belt 43.4 million miles Perihelion of Uranus: Perihelion of Neptune:
(69.8 million km) 1,703.4 million miles 2,761.6 million miles
Aphelion of Mars: Aphelion of Earth: (2,741.3 million km) (4,444.5 million km)
154.9 million miles 94.5 million miles Aphelion of Venus:
(249.2 million km) (152.1 million km) 67.7 million miles
(108.9 million km) Inner
planetary orbits
THE INNER PLANETS Average orbital speed
These four planets are small and of Jupiter: 8.1 miles/sec Sun
dense compared to most of the (13.1 million km/sec)
outer planets. The terrestrial Perihelion of
planets are warmer, and they spin Average orbital Saturn: 840.4
more slowly than the outer five. speed of Saturn: Perihelion of Jupiter: million miles
All the planets orbit the Sun 6 miles/sec (9.7 460.1 million miles (1,352.6
counterclockwise. At “perihelion,” million km/sec) (740.5 million km) million km)
a planet is closest to the Sun. A
planet reaches its “aphelion” when Saturn
farthest away from the Sun.

Aphelion of Neptune: Aphelion of
2,824.5 million miles Saturn: 941.1 Aphelion of Jupiter: Jupiter
(4,545.7 million km) million miles Uranus
(1,514.5 507.4 million miles
million km) (816.6 million km)
Average orbital speed of Uranus:
4.2 miles/sec (6.8 km/sec)
Aphelion of Uranus:
1,866.4 million miles
(3,003.6 million km)
Direction of orbital motion
Pluto
Neptune THE OUTER PLANETS
Average orbital These five are termed “Jovian” planets, after
speed of Neptune: Jupiter, the largest planet. Jupiter, Saturn,
3.4 miles/sec Uranus, and Neptune are “gas giants,” mostly
(5.4 km/sec) Average orbital composed of hydrogen and helium. Tiny Pluto
speed of Pluto: 2.9 is the outermost world. Its plane of orbit tilts
miles/sec (4.7 km/sec) far from those of the other planets.
Aphelion of
Mars is 128.4 Pluto: 4,538.7
million miles million miles/sec
(206.6 million (7,304.3 km/sec)
km) from the
Sun at
its closest
approach Mars is 154.9 million
miles (249.2 million km)
from the Sun
at its farthest Sun Mars is the fourth
planet from the Sun

PLANETARY NEIGHBORS
AN EGG AND A CIRCLE Mars is 4,220 miles (6,794 km)
Mars has an egg-shaped in diameter, about half Earth’s
orbit, while Earth’s is a circle size. A Martian sol is 39
about 93 million miles (149.6 minutes longer than Earth’s
million km) from the Sun. The 24-hour day, and a Martian year
planets are closest every two years and two is almost twice as long as Earth’s
months, when both are nearest the Sun. 365-day year. Gravity on Mars is
Earth’s almost Then, Mars is “in opposition”—on the only about one-third Mars is about half
circular orbit opposite side of Earth from the Sun. as strong as Earth’s. the size of Earth

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