Sources of information - PlanetFacts.net, NASA Solar System Exploration, brittanica.com,
universetoday.com,
Mercury Facts
Mercury is the planet nearest to the Sun. It has a diameter of 3,031 miles, about two-fifths the
Earth's diameter. Because of Mercury's size and nearness to the brightly shining Sun, the planet
is often hard to see from Earth without a telescope. The ancient Romans named it Mercury in
honor of the swift messenger of their Gods. Mercury has no moons.
 The Sun appears 2 and a half times larger in Mercury's sky compared to the Earth's.
 Mercury has virtually no atmosphere. It however has small traces of an atmosphere which
consists minute quantities of Hydrogen, Oxygen, Sodium, Potassium and argon.
 Because of the lack of atmosphere, Mercury's sky is black and the stars probably can be
seen during the day.
 System with an iron core like Earth.
 The surface of Mercury is heavily cratered, looking much like our moon.
 The Sun's rays are about seven times as strong on Mercury as they are on the Earth.
Features on Mercury
 There are huge cliffs on Mercury. Some are hundreds of miles long and two miles high.
 Caloris Basin – This huge basin (about 800 miles across) was probably formed by a
collision with a large asteroid. It is surrounded by mountains, some as high as two miles.
Sources of information - PlanetFacts.net, NASA Solar System Exploration, brittanica.com,
universetoday.com,
Venus Facts
Venus is the second planet from the Sun and the closest planet to Earth. It is named after The
Roman Goddess of love and beauty, but it's extremely hot and deadly atmosphere makes it
impossible for any human astronaut to explore its surface. The diameter of Venus is about 7,520
miles which is about 400 miles smaller than that of Earth.
 Venus is known as Earths' twin sister because of its similar size and proximity to each
other.
 Venus rotates so slowly that it orbits the Sun faster than it can make one whole rotation
on its axis. In other words, Venus has a longer day than year.
 Venus is one of the most widely explored planets aside from our own Earth. Numerous
space probes have been sent to Venus to gather data and some have landed on the
surface.
 It is believed that Venus used to have bodies of water similar to Earth, but dried up over a
period of 300 million years when the Sun began admitting more solar energy after the
Sun's infancy stage.
 The clouds of Venus are filled with sulfuric acid.
 Venus has mountains that are higher than Earth. Maat Mons is more than 5 miles high.
 Venus is the brightest planet viewed from Earth.
 The planet rotates from East to West. The only other planet that does this is Uranus.
 The atmospheric pressure on Venus is over 90 times Earth pressure (this is the same
pressure about 2/3 miles deep in the ocean).
Features on Venus
 Surface is covered by clouds.
 Most of the surface of Venus is covered by smooth volcanic plains, and it’s dotted with
extinct volcanic peaks and impact craters.
Sources of information - PlanetFacts.net, NASA Solar System Exploration, brittanica.com,
universetoday.com,
Mars Facts
Mars is the only planet whose surface can be seen in detail from the Earth. It is reddish in color, and was named
after the bloody red God of war of the ancient Romans. Mars is the fourth closest planet to the Sun. The
diameter of Mars is 4,200 miles, a little over half that of the Earth. Mercury is the only planet smaller than
Mars.
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Mars is red because it is rusty. There is a lot of iron in the soil, and the air on Mars has made it turn redjust like rusty iron on Earth.
One of Mars' moons, Phobos, is moving closer and closer to Mars. Scientists think that one day it will
crash into Mars.
Like Earth, the poles of Mars are covered in ice. The ice becomes thicker in the winter.
At its brightest, Mars outshines every other planet apart from Venus.
In 1996 NASA, while studying the ALH 84001 meteorite of Martian origin found in Antarctica in 1984,
announced that fossilized micro-organisms from Mars might be present in it.
Valleys and Canyons on Mars suggest that the planet once had large amounts of surface water.
The Moon Deimos is the smaller of Mars' two moons.
Deimos was named after an attendant of the Roman God, Mars (Deimos is Latin for "panic.”)
Phobos is the larger of Mars’ two moons.
Phobos was named after an attendant of the Roman God, Mars. (Phobos is Latin for "fear.")
Phobos was discovered on 17 August 1877 by Asaph Hall.
Deimos was discovered on 11 August 1877 by Asaph Hall.
Deimos and sets twice a day.
Phobos makes three complete orbits around Mars every day.
On Phobos, objects weigh .06 times what they weigh on Earth. If you weighed a hundred pounds, you
would weigh 6 pounds on Phobos.
The gravity on Phobos and Deimos is so weak, if you ran fast enough and jumped, you would go into
orbit around the moons.
Features on Mars
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Valles Marineris - Valles Marineris stretches 2,500 miles across the planet. Typical canyons are 125
miles across and have walls 1–3 miles deep.
Olympus Mons – This is the largest volcano in the Solar System. It is 435 miles across and is 14 miles
high.
There is evidence that there were rivers and oceans on Mars in the distant past.
Sources of information - PlanetFacts.net, NASA Solar System Exploration, brittanica.com,
universetoday.com,
Jupiter Facts
Jupiter is the largest planet in our Solar System. Ancient Astronomers named Jupiter after the
king of the Roman Gods. Jupiter is the 5th closest planet to our Sun. The atmosphere of Jupiter
consists of about 84 percent Hydrogen and about 15 percent helium, with small amounts of
acetylene, ammonia, ethane, methane, phosphine, and water vapor.
 Jupiter has a mass 318 times greater than the Earth's and a diameter that is 11 times
larger.
 The mass of Jupiter is 70% of the total mass of all the other planets in our Solar System.
 Jupiter's volume is large enough to contain 1,300 planets the size of Earth.
 Jupiter rotates faster than any planet in the Solar System.
 The great red spot on Jupiter is a storm that has been going on for over 300 years.
 You can fit 100 Earths into Jupiter's great red spot.
 Jupiter has a ring just like Saturn and Uranus.
 Jupiter is covered by an ocean of hydrogen with a sludge-like consistency.
 Unlike other planets, Jupiter sends out a strong radio radiation that can be detected on
Earth.
 In 1994, pieces of a comet called shoemaker-Levy 9 broke apart and crashed into Jupiter.
This left patches in Jupiter's atmosphere that lasted for many months.
 The four largest moons of Jupiter were discovered by Galileo in 1610.
 There may be a liquid ocean under the icy surface of the moon Europa.
 The moon Ganymede is the largest moon in the Solar System. It is larger than Mercury.
 The moon Callisto’s surface is the most heavily cratered object in the Solar System.
 Callisto has the oldest landscape in the Solar System.
Major Features
 The Great Red Spot – This swirling red oval storm us twice the size of Earth. It has been
observed since 1878.
 The Moon Io - Because Io is the closest to Jupiter, tidal effects squeeze the moon like a
rubber ball, heating the interior. This energy is released in spectacular volcanic eruptions.
Io’s volcanoes were discovered by the American probe Voyager 1, making the moon the
first place beyond Earth where active volcanoes were observed.
 All the planets in our Solar System could be placed inside the planet Jupiter.
Sources of information - PlanetFacts.net, NASA Solar System Exploration, brittanica.com,
universetoday.com,
Saturn Facts
Saturn is the second largest planet. Only Jupiter is larger. Saturn has seven thin, flat rings
around it. A couple of planets have rings, but their rings are much fainter than those around
Saturn. Saturn's diameter at its equator is 74,600 miles which is almost ten times that of Earth.
The planet can be seen from Earth with the unaided eye, but its rings cannot. Saturn was the
farthest planet from the earth that the ancient astronomers knew about. They named Saturn after
the Roman God of agriculture.
 Saturn has the lowest density of all the planets in the Solar System. It is so light that it
could actually float on water if there was an ocean big enough to hold it.
 Saturn's rings are made up of billions of pieces of rocks and dust.
 Saturn has no solid surface. It is a giant ball of gas, but it does have a solid inner core.
 The temperature difference between the poles and the equator is very small on Saturn.
 The atmosphere of Saturn comprises mostly of Hydrogen and Helium.
 Galileo was the first astronomer to observe Saturn's rings...
 He could not see the rings clearly with his small telescope and thought they were large
Satellites.
 Titan is the only moon in the Solar System with a thick atmosphere.
 Titan is larger than the planet Mercury.
 Titan has lakes and rivers made of liquid methane on its surface.
 Titan was discovered on 25 March 1655 by the Dutch astronomer Christiaan Huygens.
 There are active geysers on the south pole of the moon Enceladus. It is responsible for
creating Saturn’s E-ring.
 The surface of Enceladus is similar to a skiing slope.
 The moon Mimas has a huge crater in the northern hemisphere. The moon looks like the
Star Wars Death Star.
Major Features
 The rings – They are one of the most distinct planetary features in the Solar System. They
have a diameter of 170,000 miles, but they are thin, with a thickness of only 330 feet. The
rings are made up of many particles of rock and dust.
 South Polar Geysers on Enceladus - Enceladus, has a smooth, almost featureless surface
covered with ice. At the south pole there are several ridges from which gigantic geysers
spew water thousands of miles into space and form Saturn’s E-ring. The geysers likely
come from an ocean of liquid water underneath the ice. Where there is water and energy,
there may be life.
Sources of information - PlanetFacts.net, NASA Solar System Exploration, brittanica.com,
universetoday.com,
Uranus Facts
Uranus is the seventh planet from the Sun and is named after the Greek God of the sky in Latin.
It is the only planet whose name came from a figure in Greek mythology as opposed to Roman
mythology.
 Because of the strange way it spins, nights on some parts of Uranus can last for more than
40 years.
 The planet's most extraordinary feature is the tilt of its rotational axis, which is almost
perpendicular to the plane of the ecliptic, which means that it alternately has its north
pole and its south pole turned towards the Sun.
 Even though Neptune is further from the Sun, Uranus is the coldest planet in the Solar
System.
 In many Asian languages, Uranus' name is translated into “Sky king star”.
 Uranus mass is more than 14 times larger than Earth.
 Uranus and Neptune are both also known as Ice Giants.
 It is the second least dense planet after Saturn.
 The planet was discovered in 1781 by William Hershel.
 Voyager 2 pictures showed Uranus to be a featureless globe.
 It takes 30,685 Earth days for Uranus to complete an orbit around the Sun.
 The moon Miranda was discovered in telescopic photos of the Uranian system by Gerard
P. Kuiper on 16 February 1948 at the McDonald Observatory in western Texas.
 It is believed Miranda was struck by a large body and broken into pieces. There was
enough gravity present to pull the pieces back together.
Sources of information - PlanetFacts.net, NASA Solar System Exploration, brittanica.com,
universetoday.com,
Neptune Facts
After Pluto was declassified as a planet, Neptune became the farthest planet from the Sun.
Neptune's diameter is about 30,200 miles or almost 4 times the Earth's diameter. The planet was
named after the Roman Sea God.
 Neptune is so far away that it took the space probe Voyager 2, 12 years to reach it.
 Neptune is the stormiest planet. The winds there can blow up to 1,240 miles per hour,
that is three times as fast as Earth's Hurricanes.
 The planet has a system of thin dark rings but they are incomplete rings and are best
described as arcs.
 Neptune is a sea blue color due to the methane gas in its atmosphere.
 Neptune only receives 1/900 of the solar energy that reaches Earth.
 Neptune has its own heat source; it emits a quantity of energy 2.7 times greater than it
receives.
 Neptune is 30 times farther from the Sun as is the Earth.
 The atmosphere is made up of hydrogen, helium and methane.
 Neptune has a rocky core.
 The moon Triton is the largest of the Neptune moons.
 There are numerous active liquid nitrogen geysers on Triton.
 Triton is the only large moon that orbits clockwise around Neptune. All other large
moons orbit their planet counterclockwise.