1. Mercury
Mercury is the smallest planet in our Solar System with the smallest volume of any planet.
It has a volume which is only 5.4% of Earth’s.

2. Fast Mercury Facts Diameter (km) 4879.4 Average distance from Sun
0.387 AU (57,909,175 km)
Rotation period (length of day in Earth days)
58.65
Revolution period (length of year in Earth days)    
87.97
Mean surface temperature (K)
452 = 353 F
Maximum surface temperature (K)
700 = 800 F
Minimum surface temperature (K)
100 = -279 F

3. Mercury
The first American spacecraft mission to Mercury was in by Mariner 10.
Mariner 10 photographed 45% of Mercury’s surface.
Mercury’s surface has many craters and cliffs.
Mercury has no moons.

4. Venus Venus is only slightly smaller than Earth.
That is 86% of the Earth’s volume. This may not seem like Venus is that close in size to our planet,  but Venus is closer in size to Earth than any other planet is.

5. Venus Fast Facts Diameter (km) 12104 Average distance from Sun
0.723 AU (108,208,930 km)
Rotation period (length of day in Earth days)
(retrograde)
Revolution period (length of year in Earth days)    
224.7
Mean surface temperature (K)
726 = 847 F

6. Venus Venus is commonly referred to as Earth’s twin.
In 1962 Mariner 2 flew past Venus and sent back information about it’s atmosphere and rotation.
Venus’s dense atmosphere causes the greenhouse effect which results in the hot surface temperatures.
Venus has no moons.

7. Earth
Earth is the largest of the four inner planets, although it is nothing compared to the gas giants.

8. Earth Fast Facts Diameter (km) 12756 Average distance from Sun
1 AU (149,597,890 km)
Rotation period (length of day in Earth days)
1 (23.93 hours)
Revolution period (length of year in Earth days)
365.26
Mean surface temperature (K)
281 = 46 F
Mean maximum surface temperature (K)
310 = 98 F
Mean minimum surface temperature (K)
260 = 8 F

9. Mars Mars is actually a rather small
It is only 15% of Earth’s volume. You could put over six planets the size of Mars inside the Earth.

10. Mars Fast Facts Diameter (km) 6787 Average distance from Sun
1.524 AU (227,936,640 km)
Rotation period (length of day in Earth days)
1.026
Revolution period (length of year in Earth days)    
686.98
Maximum surface temperature (K)
310 = 98 F
Minimum surface temperature (K)
150 = -189 F

11. Mars Mars has the largest volcano in our solar system, Olympus Mons.
There is evidence that Mars may have had liquid water on its surface at one point.

12. Mars
The temperature difference between day and night result in strong winds and can cause global dust storms.
Mars has two small, irregularly shaped moons.
Phobos is about 25 km in diameter.
Phobos orbits around Mars every 7 hours.
Deimos is about 13 km in diameter.
Deimos orbits Mars every 31 hours.

13. Jupiter
The largest planet in our Solar System, Jupiter’s size is astounding.
To show what this number means, you could fit 1321 Earths inside of Jupiter. It is hard to imagine how large that actually is.

14. Jupiter Fast Facts Diameter (km) 142,800 Average distance from Sun
5.203 AU (778,412,020 km)
Rotation period (length of day in Earth days)
0.41 (9.8 Earth hours)
Revolution period (length of year in Earth years)
11.86
Mean surface temperature (K)
120 (cloud tops) = -243 F

15. Jupiter At least 63 moons orbit Jupiter.
In 1610 Galileo Galilei was the first person to see Jupiter’s four largest moons.
Io: most volcanically active object in the solar system.
Europa: rocky interior is covered by a smooth 5 km thick crust of ice. A liquid ocean may exist under the ice crust. Has a thin oxygen atmosphere.

16. Jupiter
Ganymede: the largest moon in the solar system (larger than Mercury). Heavily cratered crust of ice covered with grooves with a rocky interior. Thin oxygen atmosphere.
Callisto: Heavily cratered crust with a mixture of ice and rock throughout the interior.

17. Saturn Saturn is the second largest planet in the Solar System.
Although it is only a fraction of the size of Jupiter, you could fit 764 Earths inside of the gas giant.

18. Saturn Fast Facts Diameter (km) 120660 Average distance from Sun
9.537 AU (1,426,725,400 km)
Rotation period (length of day in Earth days)
0.44 (10.2 Earth hours)
Revolution period (length of year in Earth years)
29.46
Mean temperature (K)
88 K = -301 F

19. Saturn At least 47 moons orbit Saturn.
Titan is Saturn’s largest moon (larger than Mercury)

20. Uranus Uranus is a large planet
You could fit a little more than 63 Earths inside of Uranus.
Like the other gas giants, it is not very dense. Made up mostly of gas, the planet is only about 14.5 times more massive than Earth is.

21. Uranus Fast Facts Diameter (km) 51118 Average distance from Sun
19.19 AU (2,870,972,200 km)
Rotation period (length of day in Earth days)
0.72 (17.9 Earth hours)(retrograde)
Revolution period (length of year in Earth days)
30,685 (84 Earth years)
Mean temperature (K)
59 = -353 F

22. Uranus Uranus has at least 27 moons. Titania is Uranus’s largest moon.
Methane gives Uranus it’s bluish-green color. Methane absorbs the red and yellow light and clouds reflect the green and blue.
Uranus’s axis of rotation is tilted on its side compared with the other planets. Scientists believe a collision knocked Uranus on its side.

23. Neptune
Neptune is the smallest gas giant in our Solar System, but it is still much larger than any of the inner planets.
Neptune’s volume is equal to about 57 Earths.
Even though Neptune’s volume is much greater than the Earth’s is, the gravity on Neptune is only about 14% greater than it is on Earth. This is due to the gas giant’s small mass.

25. Fast Facts Neptune Diameter (km) 49528 Average distance from Sun
30.07 AU (4,498,252,900 km)
Rotation period (length of day in Earth days)
0.67 (19.1 hours)
Revolution period (length of year in Earth days)
60,190 (164.8 Earth years)
Mean temperature (K)
48 = -373 F

26. Neptune
Neptune is blue green in color because of the methane in its atmosphere.
Neptune has at least 13 moons.
Triton is Neptune’s largest moon.