Planet Facts:
My Very Energetic Mother Just Served Us Noodles
Our Solar System – in order from the sun:

Sun – Mercury – Venus – Earth – Mars – Jupiter – Saturn – Uranus – Neptune

Mercury

• The planet Mercury is the closet to the Sun.  It has the greatest temperature range of any planet or satellite in the solar system – a blazing 427 degrees Celsius (800.6°F) on the side closest to the Sun, and 183 degrees Celsius (361.4°F) on the night side.
• It rotates on its axis once every 58.9 days and circles the Sun once every 87.9 days.  If you wanted to stay up for a sunrise-to-sunset day on Mercury, you would be awake for two Mercurian years (a total of 176 Earth days).
• One Mercury day equals 58.6 Earth days.
• Mercury has no moons (satellites).
• Mercury is the smallest planet. Mercury is about one-third the size of Earth.
• The only spacecraft to explore (fly by) Mercury was Mariner 10 in 1974-1975.  It imaged about half of the planet on its three encounters, so half of the planet is still unexplored.
• 1610 – Italian astronomer Galileo Galilei made first telescopic observation of Mercury.
• 57.8 million Kilometers from the Sun

Venus

• If Earth had a twin, it would be Venus.  The two planets are similar in size, mass, composition, and distance from the Sun.
• Venus is the second planet from the Sun.
• Venus rotates from east to west (opposite of the Earth), so the sun rises in the west and sets in the east.
• Venus has a thick, swirling cloud cover.  Thanks to radar telescopes and radar imaging systems orbiting the planet, we have been able to see through it to the surface – vast plains covered by lava flows and mountains or highlands with lots of craters.
• Venus has a scorching surface temperature of about 482 degrees Celsius (899.6°F).  Heat trapped under Venus’ heavy clouds of carbon dioxide can’t escape into space, so Venus is hotter than Mercury.
• Because of its convenient orbit and scientific interest, Venus has been visited by more spacecraft, both U.S. and Russian, than any other planet, with flyby missions, orbiters, surface landers, and even atmosphere-floating balloons.
• Venus has no moons. Venus has no oceans.
• One Venusian year is equal to 0.62 Earth years.
• One Venusian Day is equal to 243 Earth days.
• 108.2 million Kilometers from the Sun.

Earth

• Earth, our planet, is the only planet in the solar system known to harbor life.
• Earth is the third planet from the Sun and the fifth largest in the solar system.
• The Earth is 70 percent covered with oceans, which are the principal life habitat on Earth.
• The Earth has day and night because of the planet’s rotation on an imaginary axis.
• The Earth has changing seasons because of the tilt of the Earth on its axis.
• The Earth has an atmosphere that protects us from meteors, most of which burn up before they can strike the surface.
• The Earth was last in its present position in the Milky Way when the age of dinosaurs began!  (A complete circle around the Milky Way takes 225 million years.)
• 1957 – Sputnik 1 U.S.S.R. became the first artificial satellite of the Earth.
• The Earth has one moon (satellite).
• It takes the Earth 23.93 hours to rotate completely around its axis (thus our 24 hours in one day).
• It takes the Earth 365.26 days (thus our 365 days per year) to rotate around the Sun.

Mars

• Mars, the Red Planet, has inspired wild flights of imagination over the centuries, and an intense scientific interest.  Mars was thought to be the best bet for extraterrestrial life, until space exploration.
• Mars is called the Red Planet because of chemical weathering of its iron-rich rocks.
• Mars may have had primitive life long ago.  A meteorite from Mars found in Antarctica contains clues that make scientists think so.
• Mars is self-sterilizing.  Biologists believe the Sun’s ultraviolet radiation, the dryness of the soil, and the soil chemistry prevent formation of living organisms in the soil.
• Mars has shown itself to be the most Earth-like of all of the planets.
• It has polar ice caps that grow and recede with the changes of seasons, and markings that appear to be similar to water channels on Earth.
• Mars is a small rocky planet that developed relatively  close to the sun and has been subjected to some of the planetary processes associated with the formation of other “terrestrial” planets (Mercury, Venus, Earth, and Mars), including: volcanos, impact events, and atmospheric effects.
• Mars has two moons (satellites) named Phobos (fear) and Deimos (panic).
• Mars’ atomosphere is mainly carbon dioxide.
• Maximum distance from the Sun – 249 million km
• Minimum distance from the Sun – 206 million km
• June 2008 – Water ice found on Mars.

Jupiter

• Jupiter has 16 moons (satellites), a ring system, and a complex atmosphere.
• Jupiter reigns supreme among the eight planets, containing two-thirds of the planetary mass of the solar system.
• Jupiter contains more matter than all the other planets combined.
• Jupiter is ringed by three narrow, dusty, barely visible rings, probably less than 10 km (6.2 miles) thick and about 6,500 km (4,000 miles) wide.
• Jupiter has an Easter-egg appearance due to its colorful band of clouds.
• Jupiter is known for its Great Red Spot, a hurricane-like storm cell so large that it could swallow Earth.
• 1610 – Italian astronomer Galileo Galilei discovered four moons orbiting Jupiter (Io, Europa, Ganymead, and Callisto-the Galilean Satellites).
• 778.3 million Kilometers from the Sun
• One Jovian year is equal to 11.86 Earth years.
• One Jovian day is 9 hours, 55 minutes.

Saturn

• Saturn is the sixth planet from the Sun and is one of the five planets visible from Earth without a telescope.
• Saturn is a giant, gaseous planet.
• Saturn has 7 rings.
• Saturn has 18 known moons (satellites), but Hubble Space Telescope sightings may reveal more.
• Saturn has many rings as a record album has grooves, and they have spokes.
• Saturn is made of materials lighter than water.  If a large enough ocean could be found, Saturn could float in it.
• Saturn is surrounded by a dull yellow haze, but underneath blow winds ten times stronger than an Earth hurricane.
• Saturn is the most distant planet visible to the naked eye.
• 1610 – Galileo Galilei discovered Saturn’s rings.
• One Saturnian day is 10 hours, 40 minutes.
• Saturn is 1,429.4 million Kilometers from the Sun.

Uranus

• Uranus has at least 15 moons (satellites).
• Uranus has 11 rings; the first nine rings were discovered in 1977.
• Uranus looks blue-green because of methane gas in its atmosphere.
• Uranus is tipped on its side, possibly the result of a collision with a planet-sized body early in the solar system’s history.
• 1781 – Sir William Herschel discovered Uranus.
• One Uranian year is equal to 84.01 Earth years.
• One Uranian Day is 17 hours, 14 minutes.
• Uranus is 2.871 billion Kilometers from the Sun.

Neptune

• 1846 – German astronomer Johann Galle discovered Neptune using predicted location (mathematical predictions) provided by Adams and Leverrier.
• Neptune has eight moons (satellites), six of which were found by Voyager.
• Neptune has four narrow and very faint rings of varying thicknesses.
• Neptune could contain nearly 60 Earths if it were hollow.
• Neptune is aqua-blue color because its clouds contain methane ice crystals.
• Neptune has the strongest winds of any planet.
• Triton is the largest satellite (moon) of Neptune.
• Neptune is 4,501.2 billion Kilometers from the Sun.

Dwarf Planet Pluto

(Pluto was designated a dwarf planet on 08/24/06.)

(Scientists are currently considering calling dwarf planets “plutoids”)

• Pluto’s orbit is the most elliptical and tilted and has a moon (named Charon) close to its own size.  Pluto’s moon is smaller than Earth’s moon!
• Because of its great distance, Pluto has never been visited by spacecraft.
• 1930 – Pluto was discovered.
• Pluto is normally the farthest away from the sun than the planets.  But because of its unusual orbit, Pluto trades places with Neptune for 20 years at a time.  It returned to its usual rank in 1999.
• Pluto’s average distance from the Sun is 6 billion Kilometers.

More Solar System Facts:

• The four planets closest to the Sun – Mercury, Venus, Earth, and Mars – are called terrestrial planets because they have solid rocky surfaces.
• The four large planets beyond the orbit of Mars – Jupiter, Saturn, Uranus, and Neptune – are called gas giants.
• Tiny, distant, dwarf planet Pluto has a solid but icier surface than the terrestrial planets.
• Nearly every planet – and some of the moons – has an atmosphere.
• Earth’s atmosphere is primarily nitrogen and oxygen.
• Venus has a thick atmosphere of carbon dioxide, with traces of poisonous gases such as sulfur dioxide.
• Mars’ carbon dioxide atmosphere is extremely thin.
• Jupiter, Saturn, Uranus, and Neptune are primarily hydrogen and helium.
• When Pluto is near the Sun, it has a thin atmosphere, but when Pluto travels to the outer regions of its orbit, the atmosphere freezes and “collapses” to the planet’s surface.  In this regard, Pluto acts like a comet.
• There are 61 natural satellites (moons) ranging from bodies larger than our own Moon to small pieces of debris.
• Five planets can be seen from Earth without telescopes: Mercury, Mars, Venus, Jupiter, and Saturn.
• The two other planets – Uranus and Neptune can be seen with telescopes.
• There are thousands of small bodies such as asteroids and comets.  Most of the asteroids orbit in a region between the orbits of Earth and Mars, while the home of comets lies far beyond the orbit of Pluto, in the Oort Cloud.
• Saturn, Jupiter, Uranus, and Neptune have ring systems.  Saturn’s by far is the largest.  Particles in these ring systems range in size from dust to boulders to house sized, and may be rocky and/or icy.
• Most of the planets have magnetic fields which extend into space and form a “magnetosphere” around each planet.  These magnetospheres rotate with the planet, sweeping charged particles with them.  The Sun has a magnetic field, the heliosphere, which envelops our solar system.
• The planets orbit the Sun.

The Sun

• The Sun is the only body in our solar system that gives out a light of its own.
• The Sun is more than 100 times wider than the Earth.
• The Sun takes up as much space as 1 million planets the size of the Earth.
• The Sun is made mostly of hydrogen, which acts like a fuel to produce the energy that keeps the sun shining.
• The Sun has been shining for nearly 5 billion years, pouring out enormous amounts of energy as light and heat.
• The sun is a star.

The Moon

• The Moon, Earth’s only natural satellite, is unusually large in relation to its planet, having a diameter roughly ¼ that of Earth’s.  Thus, the two bodies are sometimes referred to as a double-planet system.
• During the Moon’s formation, very high temperatures caused extensive melting of its outer layers.  The melting resulted in the formation of the lunar crust, probably from a planet-wide “magma ocean”.
• The Moon is slightly eggshaped, with the small end of the “egg” pointing toward Earth.  This position causes the Moon to keep the same face toward Earth at all times.
• 1610 – Italian astronomer Galileo Galilei made the first telescopic observations of the Moon.
• 1969 – Apollo 11 mission made the first manned (human crew) landing on the Moon and returned samples. On July 20, 1969, at 10:56 p.m., Armstrong stepped onto the surface of the moon and spoke the famous words "that's one small step for a man; one giant leap for mankind." Indeed, one of humankind's oldest dreams had been realized.

Comets

• Comets are dirty-ice leftovers from the formation of our solar-system around 4.5 billion years ago.
• Each comet has only a tiny solid part, called a nucleus, often no bigger than a few kilometers across.  The nucleus contains icy chunks and frozen gases with bits of embedded rock and dust.  At its center, the nucleus may have a small, rocky core.
• Most comets arrive from a distant region called the Oort Cloud about 100,000 astronomical units from the Sun.
•  In addition to the comets in the Oort Cloud, billions more orbit the Sun beyond the orbit of Pluto.  This belt of comets is called the Kuiper Belt.
• As a comet begins its inward pass toward the Sun, it begins to warm up and turns from a dark, cold object into one so bright that we can see it on Earth.  This transformation occurs when the heat from the Sun vaporizes ice on the comet’s surface, causing the resultant gases to glow.
• Astronomer Englishman Edmond Halley first proved that comets are regular visitors of our solar system.  He realized that one particularly bright comet was being sighted once every 76 years or so.  Comet Halley last approached the Sun in 1986 and will be back in 2061.

                        NASA/TrendsDiscovery Guide