A Planet a day

1. A Planet a day Our solar system

2. Mercury • First planet from the sun. .387 AU • Ranked 8th in size (being the smallest of the true planets) 4.9mm • Named for the messenger to the Roman gods, Mercury is the closest planet to the Sun and as a result, revolves around our star in the least amount of time.

3. Mercury • Mercury has a solid rocky surface and like the Moon, has many craters. • Mercury has a very weak atmosphere. • Mercury goes through extremes in temperatures. Daytime temperature can reach up to 450 ºC, which is enough to melt lead. On the other hand, the planet's nighttime side can be quite cold, temperatures as low as -180 ºC have been recorded by Mariner 10. • Mercury has no moon.

5. Venus • Second planet from the sun distance is .723 AU • Rank 6th in size 12.1 mm (smaller of the planets) • Venus, named for the Roman goddess of love, is known as Earth's "sister" planet because they are very near in size, mass and density. However, the similarities end there. Venus is the planet that approaches closest to Earth and can be the brightest object in the sky, next to the Sun and Moon.

6. Venus • Venus has a solid rocky surface that is now known to be covered with craters and volcanic mountains. • Venus has clouds of sulfuric acid that cover the planet. Because of this, we cannot see its surface. • Venus has a very dense atmosphere of carbon dioxide gas (CO2) that has the property of letting in sunlight but does not permit the resulting heat to escape. • temperatures on Venus to reach up to 455 ºC. • The atmospheric pressure at the surface of Venus is 90 times that of Earth A visitor to the planet would be instantly crushed without special protection. • Venus has no moon.

8. Mars • Called the Red Planet • Mars, named for the Roman God of war • Is the 4th planet in line from the sun. 1.52 Au • Mars is 6.7 mm Ranked 7th in size (being on the small side) • Mars has a solid rocky surface rich in iron.This is what gives it a reddish colour. Among its surface features are craters, extinct volcanoes, canyons and river-like features where water may once have flowed.

9. Mars • Mars, like Earth goes through seasons that last about 6 months,(it's axis of rotation is tilted by 24o to the plane of its orbit) • Mars has polar "ice" caps, like Earth, that expand and contract with the seasons, however, they are composed of frozen carbon dioxide and water ice. • Mars has a thin atmosphere mostly composed of carbon dioxide gas (CO2), the atmospheric pressure at the surface is 150 times less than Earth's. • Winds on Mars can exceed 300 km/hr. Because of this, Mars has planet-wide dust storms that can shroud the planet for weeks at a time. • Mars has two small moons; Phobos (from the Greek, meaning fear) and Deimos (from the Greek, meaning terror).

10. Mars

11. Jupiter • Jupiter, named for the King of the Roman Gods, • fifth planet from the Sun 5.2 Au • By far the largest planet in the Solar System 142.8 mm • Jupiter has no solid surface. It is a gaseous planet composed mostly of hydrogen (85%) and helium (15%) gas. • The visible surface of Jupiter is composed of clouds characterized by dark colored belts (of ammonium hydrosulfide) and lighter colored zones (of ammonia ice crystals). • Jupiter generates more energy than it receives from the Sun. If Jupiter had been much more massive, temperatures could have been high enough for the planet to become a star.

12. Jupiter • Jupiter has the largest storm in the Solar System called the Great Red Spot. This atmospheric feature has been in existence ever since the first telescopes were trained on the planet over 300 years ago. The Great Red Spot is in rotation and is so big that Earth would fit inside about four to five times. • Jupiter has a ring discovered by a Voyager 1 photograph of the planet when it was backlit by the Sun. • Jupiter has 16 known moons. The four largest are Io, Europa, Ganymede, and Callisto.

13. Saturn • Saturn, named for the Roman God of the Harvest, • was the farthest known planet from the Sun until the discovery of Uranus in 1781. ranked 6th in order. 9.5 Au • The second largest planet in the Solar System has an intricate ring system. 120.6 mm • Saturn has no solid surface. It is a gaseous planet mostly composed of hydrogen and helium gas. • Saturn's atmosphere has clouds that are banded (similar to Jupiter's but not as colourful). • Saturn generates more heat than it receives from the Sun.

14. Saturn • Saturn has an extensive ring system. The rings have a thickness that varies from tens of meters to about 1 km. The rings are made up of thousands of tiny ringlets mostly composed of water ice and rock particles that range in size from grains of dust to objects kilometers across. • Saturn is less dense than water. As a result, it would float if we could find a big enough ocean. • Saturn has 18 known moons. Titan is one of the most interesting because it is the only moon to have an atmosphere. • Saturn's rotation period of 10 hrs. 40 min and the fact that it is a gaseous planet produces flattening at the poles and at the equator, even more so than any of the other gaseous planets.

15. Uranus The seventh planet from the Sun 19.2 Au The third largest 51.3mm named after the Greek God, Ruler of the World • Uranus has no solid surface. It is a gaseous planet composed of hydrogen and helium gas. • Current thought on the interior of Uranus holds that it may be made up of water, methane and ammonia. Uranus may have a solid rocky core.

16. Uranus • Uranus is the only giant planet to lack a "significant" internal heat source. It's rings are composed of ice and rock particles that are darker than Saturn's and almost as black as charcoal. • Uranus' axis of rotation is tilted almost parallel (97º) to the plane of its orbit. • It has 15 known moons (10 of them discovered by Voyager 2 in 1986), one of which is the most perplexing in the whole Solar System. Miranda has a surface that shows evidence of having been shattered and then reassembled more once.

17. Neptune • Neptune is named for the Roman God of the Sea • It is the 8th planet from the sun 30.11 au • The fourth largest 49.1 mm • Neptune has no solid surface. It is a gaseous planet, primarily composed of hydrogen and helium gas, with traces of methane. Its color is a bluish green. Neptune's interior may be similar to that of Uranus. • Neptune possesses an internal heat source. • hemisphere.

18. Neptune • Neptune has a dynamic atmosphere. Cloud features and a giant storm system similar to Jupiter's Great Red Spot were discovered by Voyager 2. Neptune's large storm system is called the Great Dark Spot and is located in the planet's southern • Neptune has rings that are different from those found at Jupiter, Saturn, and Uranus. They don't circle the planet completely, but are partial rings called "ring arcs". • Neptune has 8 known satellites, six of them were discovered by Voyager 2.

19. Pluto (no longer a planet) • Smallest planet in the Solar System 2.3 mm and 39.545 au from the sun • Named for the Roman God of the Underworld • Pluto is unlike any of the other planets because it is believed to be mostly composed of frozen ices of water, methane and ammonia. • Pluto has a very negligible atmosphere of methane. • Charon, its only known satellite, is unusually large compared to its host planet. It is about 1/2 the size of Pluto. • Charon was discovered from Earth in 1978 and like Pluto is believed to be composed of frozen ices. • No longer considered a planet because it has not “cleared the neighborhood”