The Closest Planet to the Sun – Mercury.
Mercury, a small, lifeless planet, and the closest planet to the sun. On Mercury's rocky surface you can find craters, steep cliffs, and deep canyons.
During the day, the heat is intense. But at night, temperatures drop to 300°F below 0(-183°c)!
QUICK FACTS
Name: Mercury
Type: Planet
Mean Diameter at Equator: 3,240 miles (4,878 kilometers)
Mass: 0.055 of Earth's mass
Density: 5.43 g/cm3
Surface Gravity: 0.387 of Earth's gravity
Mean Distance from Sun: 36 million miles (58 million kilometers). Mercury is the closest planet to the sun.
Composition: Rocky; has no atmosphere
Rotation Period (Length of One Day): 59 Earth-days
Period of Revolution (Length of One Year): 88 Earth-days
Moons: None
Mean Temperature: Night: -297°F (-183°C); day: 800°F (427°C)
SIZE
Mercury is a small ball of solid rock. It is about the same size as our moon. The diameter of Mercury is about one third the diameter of Earth. Among the planets of our solar system, only Pluto is smaller than Mercury.
Composition
Mercury is made up of rock and metals. Its core is very large and consists of iron and nickel. Mercury is one of the richest sources of iron in our solar system, but the iron is located so deep in the planet's core that it would be almost impossible to mine. Surrounding Mercury's core is a mantle made up of highly compressed molten silicate rocks. A thin, solid crust of rock covers the mantle.
Gravity
If you could land on Mercury, you would see that every small step becomes a high jump! The planet has such a weak gravitational pull, about 3/8 that of Earth, because Mercury's mass is much smaller.
Distance from the Sun
The closest planet to the sun, Mercury travels in an orbit shaped like a flattened ellipse. As a result, the planet is sometimes as close as 29 million miles (46 million kilometers) to the sun, but then it also gets as far away as 43 million miles (70 million kilometers).
If there were a contest for the most elliptical orbit in the solar system, Mercury would come in second, after Pluto.
Period Of Revolution (Length Of OneYear)
Mercury revolves around the sun faster than all the other planets! It travels at a speed of 105,400 miles (170,000 kilometers) per hour. This is why Mercury has the shortest year of all the planets in our solar system. It lasts only 88 days!
Rotation Period (Length of One Day)
Mercury spins around its axis very slowly. About 59 days go by on Earth before Mercury completes one day of its own.
Climate
Mercury has no weather because it has no real atmosphere. Scientists believe that Mercury's atmosphere escaped to outer space long ago, due to the planet's weak gravity and the sun's intense radiation. Lately, a trace of a tenuous atmosphere was observed on Mercury: it is made of sodium atoms, a substance we know to be a solid metal on Earth. However, this very thin atmosphere is nothing like the layer of air that envelopes us: this is why the sky on Mercury is always black.
Mercury spins so slowly about its axis that one side of the planet stays in the sunlight for a long period of time. As a result, that half of the planet becomes extremely hot. At the same time, the opposite side of the planet is getting no sunlight at all, so it becomes freezing cold!
Looking for Mercury
Because Mercury is so close to the sun, it is not easy to observe the planet. It appears briefly, for an hour or so, just before sunrise or just after sunset. For long periods of time, Mercury cannot be seen at all. This occurs when the planet passes in front of or behind the sun and gets lost in its glare.
Every few years, Mercury comes directly between Earth and the sun, on the same plane. This situation is called a transit. When this happens, Mercury looks like a tiny black dot on the brilliant disk of the sun. Astronomers can observe the transit of Mercury with special telescopes that prevent damage to their eyes.
Earth's Twin-Venus
Early in the morning, before the sun rises, or at day's end, just after sunset, you might catch a glimpse of a glowing spot in the sky. You may think it is a star, but it is actually a planet, Venus.
From afar, Venus looks extremely bright, but when seen up close, it has a different face altogether. A dense, heavy atmosphere wraps the planet in intense heat and hides it beneath a thick veil of swirling clouds made of poisonous acid.
QUICK FACTS
Name: Venus
Type: Planet
Mean Diameter at Equator: 7,500 miles (12,100 kilometers)
Mass: 0.81 of Earth's mass
Density: 5.25 g/cm3
Gravity: 0.9 of Earth's gravity
Mean Distance from Sun: 67 million miles (108 million kilometers). Venus is the second planet from the sun.
Composition: Rocky surface; atmosphere consisting mostly of carbon dioxide
Rotation Period: 243 earth-days
Period of Revolution: 225 earth-days
Moons: None
Temperature: About 860°F (460°C)
SIZE
Venus is often called Earth's twin. The two planets are similar in size, structure, density, and gravity.
The diameter of Venus is 7,500 miles (12,100 kilometers), and the diameter of Earth is 7,910 miles (12,756 kilometers).
Composition
Venus and Earth have a similar composition. Both planets have a metallic core that contains iron and nickel. A rocky mantle and crust surround their core.
But is Earth's atmosphere like the one on Venus? Luckily for us, it isn't. Venus's blanket of gases is very different from Earth's.
Gravity
Because Venus and Earth have almost the same mass, their surface gravity is also almost the same.
Surface
Although Venus is fairly close to us, scientists have a hard time gathering information on the properties of its surface. Imagine how challenging it is to study the surface of a planet that has such dense layer of clouds, that completely obscures it from sight.
Distance from the Sun
Located between Mercury and Earth, Venus is the second planet from the sun. Unlike the other planets, Venus has an almost circular orbit and stays about the same distance from the sun throughout its orbit. The shape of the other planets' orbits is elliptical.
Period Of Revolution (Length Of One Year)
A year on Venus is shorter than a year on Earth. Venus orbits the sun in a little more than 224 days.
Why does Venus have a shorter year than we do? First, Venus is fairly close to the sun, so it has a smaller distance to travel. Second, Venus travels very quickly. Mercury is the only planet in our solar system that moves around the sun faster than Venus.
Rotation Period (Length of One Day)
Venus rotates about its axis very, very slowly. For this reason, a day on Venus is extremely long, 243 earth-days from sunrise to sunset!
Venus's rotation is unusual in another way, too. It rotates on its axis in the opposite direction of the other planets and the sun. That means that on Venus, the sun rises in the west and sets in the east!
Planet Earth - Our Home In Space
This is Earth, our planet and our home in space. Seen from thousands of miles away, Earth is a patchwork of white clouds, golden continents, and blue oceans. Teeming with the diversity of life, ours is a very special planet. Earth is the only planet in our solar system known to have liquid water on a solid surface. The water on Earth is essential to life.
QUICK FACTS
Name: Earth
Type: Planet
Mean Diameter at Equator: 7,926 miles (12,756 kilometers)
Mass: 5.97x10^21 tons
Density: 5.52 g/cm3
Surface Gravity: 9.8 m/s2
Mean Distance from Sun: About 93 million miles (149,500 million kilometers). Earth is the third planet from the sun.
Composition: Rocky; atmosphere consisting of nitrogen (77.6%), oxygen (20.7%), argon, carbon dioxide, and trace compounds
Rotation Period (Length of One Day): 23 hours, 56 minutes
Period of Revolution (Length of One Year): 365.25 days
Moons: 1
Mean Temperatures: Global, 59°F (15°C); at the poles, -31°F (-35°C); at the equator, 86°F (30°C)
SIZE
Earth belongs to a group of planets that have a solid surface and are known as the inner planets or terrestrial planets. Mercury, Venus, and Mars also belong to this group. Earth is the largest, with a diameter of 7,926 miles (12,756 kilometers) at the equator.
Measurements performed by orbiting satellites have shown that Earth is not an exact sphere. It is an oblate spheroid. That means that the planet is slightly flattened at the poles and has a bulge at the equator.
Composition
Earth is one of the terrestrial planets, a group that also includes Mercury, Venus, and Mars. All of these planets are solid and are composed of rocks and metals. The layers that make up Earth are the crust, the mantle, and the core.
Surface Gravity
The mass of a body determines the force with which it attracts other bodies. This force is usually expressed as the rate at which an object falls freely to the surface of that body, a rate commonly called "acceleration." The weight of an object on Earth is determined by multiplying the object's mass by the rate of free fall (acceleration) on Earth's surface, which is 9.8 m/s2.
The 17th century physicist Sir Isaac Newton discovered the universal law of gravitation. This law states that:
* any two bodies exert a force of attraction on each other.
* the force of attraction is directly proportional to the bodies' masses and inversely proportional to the square of the distance between them.
This law explains the motion of our moon and the planets, of galaxies and stars, and also of falling apples! It explains why we can walk on the surface of our planet without flaoting away to outer space, because earth great mass pulls us toward the ground.
The Red Desert
"Dear Friend,
If only you were here with me now, in this red wilderness. The desert rocks are red, pink dust floats in the air, and even the distant sun is a pale red.
Two moons are shining above me (yes, two!). Their light is very dim, not like the light of the beautiful moon we see on Earth. Far in the distance, I can see the outline of an extinct volcano. The wind is blowing, and it's very cold here.
With love from me, on Mars"
It may not be long before someone sends a letter like this from a colony on Mars
Quick Facts
Name: Mars
Type: Planet
Mean Diameter at Equator: 4,264 miles (6,878 km)
Mass: 0.11 of Earth's mass
Density: 3.94 g/cm3
Surface Gravity: 0.379 of Earth's gravity
Mean Distance from Sun: 141 million miles (228 million kilometers)
Mars is the fourth planet from the sun
Composition: Rocky; atmosphere is thin, consisting mostly of carbon dioxide
Rotation Period (Length of One Day): 24 hours, 37 minutes
Period of Revolution (Length of One Year): 687 Earth-days
Moons: 2
Mean Temperature: -67°F (-55°C)
Size
Mars is one of the smallest planets in our solar system. Its diameter is just over half Earth's diameter. Only Pluto and Mercury are smaller than Mars.
Composition
Like Earth, Mars belongs to the group of planets that are made of rocks and minerals. The core of Mars is mostly iron. As on Earth, the crust and mantle consist of silicate rocks and metallic minerals.
The atmosphere on Mars is very thin and is composed mainly of carbon dioxide.
Spacecraft that landed on Mars have provided plenty of information about its surface. Scientists now know that the composition of the Martian rocks and soil is like that of Earth's rocks and soil, except that Mars has more iron oxide. Perhaps one day, people will be able to mine minerals on Mars and bring them back for use on Earth.
Gravity
Because Mars has a small mass, its surface gravity is relatively weak. It is about four-tenths the force of gravity on Earth. Therefore, the rate at which objects fall to the surface of Mars is much slower than on Earth.
If astronauts were to land on Mars, they would be able to jump higher and more easily than on Earth, just as on the moon.
The Surface of Mars
Mars has been nicknamed the Red Planet, and its surface is, indeed, a rusty red. The color comes from iron oxide, which you probably know as rust.
Distance from the Sun
Mars is the fourth planet from the sun. Because of its elliptical orbit, its distance from the sun varies. The mean distance is 141 million miles (228 million kilometers).
Every so often, Mars comes close to Earth, and, for a short time, the two planets travel side by side. When scientists plan a flight to Mars, they take into account the periods when the planets are close together.
Period of Revolution (Length of One Year)
Mars completes one revolution around the sun every 687 days. This means that a year on Mars is almost twice as long as Earth's year of 365 days.
Like Earth, Mars is tilted on its axis. As a result, Mars has seasons similar to those on Earth. But because the Martian year is twice as long as ours, the seasons there last twice as long.
Rotation Period (Length of One Day)
At 24 hours and 37 minutes, a day on Mars is just a little longer than a day on Earth.
JUPITER - THE GRANDEST AND BIGGEST OF ALL!
Beyond the orbits of Mars and the asteroids, a giant ball of gas is spinning at a fantastic speed around its axis. It's Jupiter, the biggest planet in our solar system.
Orbiting Jupiter are many moons and several rings.
Quick Facts
Name: Jupiter
Type: Planet
Diameter at Equator: 88,536 miles (142,984 kilometers), 11 times the diameter of Earth
Mass: 318 times Earth's mass Density: 1.33 g/cm3
Gravity: 2.54 times Earth's gravity
Mean Distance from Sun: 482 million miles (778 million kilometers). Jupiter is the fifth planet from the sun.
Composition: Gas, mainly hydrogen and helium
Rotation Period (Length of One Jovian Day): 9:50:30 hours
Period of Revolution (Length of One Jovian Year): 11.8 earth-years
Moons: 16
Temperature: -238°F (-150°C), at the crest of the clouds
Size
Jupiter is the biggest planet in the solar system.
Jupiter is so big that you can put 11 Earths along its equator, side by side, and still have room for our moon!
Jupiter has a unique shape. It is slightly flat at the poles, unlike Earth which is spherical. This flattening is caused by the rapid rotation of the planet.
Composition
Jupiter belongs to the group of planets known as gas giants. Its composition is very different from that of Earth. In fact, it is more similar to the sun.
The upper layer of atmosphere is gaseous hydrogen and helium. However, unlike the solid planets, Jupiter does not have a surface. The deeper you go into the planet, the greater the pressure and temperature.
Underneath the atmosphere is a layer of liquid hydrogen and helium. Deep inside Jupiter, the pressure is so great that the hydrogen becomes metallic! Some scientists believe that Jupiter has a small core of rock and metal.
Gravity
Jupiter is composed mainly of gas and liquid, and it has the greatest mass in the entire solar system. In fact, Jupiter's mass is greater than the combined mass of all the other planets in the solar system!
To be able to compare Jupiter's gravity to that of the Earth, we need to establish a common reference level. For the gas giants, this is usually the height which the atmospheric pressure equals the average pressure on the surface of Earth - 1 atmosphere.
At this level, Jupiter's gravity is 2.54 times larger than on the surface of Earth.
Scientists believe that Jupiter's immense gravity prevented the formation of another planet between Jupiter and Mars. Instead, hundreds of thousands of chunks of rock remain in orbit in this area. These rocks are called asteroids.
Distance from the Sun
Jupiter is the fifth planet from the sun. The average distance between Jupiter and the sun is 5.2 astronomical units. This is more than 5 times the distance between Earth and the sun.
A great distance separates Jupiter from the fourth planet, Mars. This space holds the asteroid belt.
Period of Revolution (Length of One Year)
Jupiter's orbit, like that of the rest of the planets, is slightly elliptical. Jupiter takes approximately 12 years to complete 1 orbit around the sun. A year on Jupiter lasts 4,337 earth-days!
Rotation Period (Length of One Day)
Jupiter completes 1 rotation about its axis every 9 hours and 50 minutes. This is the fastest rotation in the entire solar system! Only Saturn can match Jupiter's speedy rotation.
Many Moons
Jupiter has at least 16 moons. The largest four are called the Galilean moons, after Galileo Galilei. He discovered them in the 17th century, using a small telescope. The other moons are much smaller. Scientists believe that some of them are asteroids that were trapped by Jupiter's powerful gravity.
Climate
Photographs of Jupiter show that it is covered with colorful stripes, smudges, and fancy whirlpools. These features are clouds at various altitudes in Jupiter's atmosphere.
What are these clouds made of?
Jupiter's clouds are made up of ice crystals, water droplets, and different compounds that give the clouds their reddish-yellow color.
Both Voyager spacecraft found severe lightning storms in Jupiter's atmosphere. These storms are much more violent than the storms we know on Earth, with 1000 times the energy.
Lord of the Rings-Saturn
Orbiting our sun is a giant, yellowish ball of gas, with shiny rings and fascinating moons. It is the planet Saturn.
Saturn is extremely cold and windy. Its atmosphere is composed of hydrogen and helium, with many colorful clouds and giant storm systems. The planet is surrounded by strong radiation belts and a strong magnetic field.
Saturn is without a doubt one of the most astounding and breathtaking sights of the solar system.
Quick Facts
Name: Saturn
Type: Planet
Mean Diameter at Equator: 74,853 miles (120,536 kilometers)
Mass: 95.18 times Earth's mass
Density: 0.7 g/cm3
Gravity: 1.07 times Earth's gravity
Mean Distance from Sun: 886,200 million miles (1,429 million kilometers). Saturn is the sixth planet from the sun.
Composition: Gas, mainly hydrogen and helium
Rotation Period (Length of One Saturnian Day): 10:40 Earth-hours
Period of Revolution (Length of One Saturnian Year): 29.424 Earth-years
Moons: 22
Mean Temperature: -292°F (-180°C)
Uranus
Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. It is named after the ancient Greek deity of the sky Uranus (Ancient Greek: ), the father of Cronus (Saturn) and grandfather of Zeus (Jupiter). Though it is visible to the naked eye like the five classical planets, it was never recognized as a planet by ancient observers because of its dimness and slow orbit. Sir William Herschel announced its discovery on March 13, 1781, expanding the known boundaries of the Solar System for the first time in modern history. Uranus was also the first planet discovered with a telescope.
Name - Uranus
Type - Planet
Diameter - 25,559 ± 4 km
Mass - 8.683 e25 kg
Orbit - 2,870,990,000 km From Sun
Volume - 6.833×1013 km3
Gravity - 8.69 m/s2
Composition -Ices:Ammonia
water
ammonium hydrosulfide (NH4SH)
methane (CH4)
Period Of Revolution -
Period Of Rotation - 17 hours, 14 minutes
Neptune
Neptune is the eighth and farthest planet from the Sun in the Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third-largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times the mass of Earth but not as dense. On average, Neptune orbits the Sun at a distance of 30.1 AU, approximately 30 times the Earth–Sun distance. Its astronomical symbol is ♆, a stylized version of the god Neptune's trident.
Name - Neptune
Type - Planet
Radius - 24,764 ± 15 km
Mass - 1.0243×1026 kg
Period Of Rotation - 16 h 6 min 36 s
Discovered on September 23, 1846, Neptune was the first planet found by mathematical prediction rather than by empirical observation.
The internal structure of Neptune:
1. Upper atmosphere, top clouds
2. Atmosphere consisting of hydrogen, helium and methane gas
3. Mantle consisting of water, ammonia and methane ices
4. Core consisting of rock (silicates and nickel-iron)
1. Upper atmosphere, top clouds
2. Atmosphere consisting of hydrogen, helium and methane gas
3. Mantle consisting of water, ammonia and methane ices
4. Core consisting of rock (silicates and nickel-iron)
