There is a lot to learn about the planets in our Solar System. From the smallest to the largest, it’s fascinating to explore.
The planets in our Solar System are grouped into two groups, the rocky inner planets and the gas giants in the outer reaches. Each group has its own unique characteristics and characteristics.
Mercury
Mercury – which means “the messenger to the gods” in Greek – is the closest planet to the Sun. Its surface is scarred by craters that are named after comets and meteoroids.
As a result, Mercury has very little atmosphere and is the hottest of all the rocky planets. Its temperature is -173 degrees Celsius (-427 deg C) at the equator and -170 K (-280 deg F) at the poles.
It has a large iron core, accounting for about three-quarters of its mass. It is surrounded by a thin, rocky shell that protects the core from the harsh heat of the Sun.
Like its Moon, the Mercury surface is dotted with impact craters. These craters were formed by comets and other small objects that hit the planet when it was relatively young.
Many craters have smooth plains that are similar in appearance to the inter-crater plains on the Moon. They also show evidence of compression folds and lobate scarps, which may have occurred when the planet cooled.
Venus
Venus is a rocky planet similar to Earth in size and mass. It is often referred to as “Earth’s twin” and is located in the same part of our solar system.
It is the fourth planet from the Sun and one of our closest celestial neighbours. It is nicknamed the “love planet” and is known for its beauty.
The planet is shrouded in a dense atmosphere made of carbon dioxide and nitrogen, with a few trace gases. The dense layer traps heat, making the planet hotter than it would be without a greenhouse effect.
This thick layer creates a runaway greenhouse effect that makes the surface of Venus as hot as 900 degrees Fahrenheit (475 degrees Celsius) – enough to melt lead! The harsh environment also means that the planet is extremely dangerous for life.
Craters and volcanoes pockmark the surface of Venus, suggesting that it was once covered by oceans. Scientists think that a catastrophic event resurfaced the planet about half a billion years ago. However, they don’t know exactly what happened.
Earth
Earth, the third planet from the Sun, is the largest and most massive of the planets in our solar system. It has the largest mass, and the greatest density of all the planets – 5.51 g/cm3.
The atmosphere of Earth is rich in nitrogen and oxygen. It also contains several other gases in smaller amounts.
It is an ocean planet, with water covering about 70% of its surface. The other 30% is land.
Scientists have studied Earth in many ways, including using the full battery of modern instrumentation to learn more about its physical properties and geological history. The detailed knowledge helps us to understand how and why our planet works the way it does.
The shape of our planet is nearly spherical. It has a slight flattening in the Northern and Southern hemispheres due to its rotation on its axis.
Mars
Mars is a planet of the Solar System that has a thin atmosphere and surface features reminiscent of both the impact craters of Earth’s Moon, as well as valleys, deserts and polar ice caps. It is often referred to as the Red Planet because of its signature reddish color and is a frequently visible object in the night sky.
As with most other rocky planets in the Solar System, Mars’ surface has been extensively studied and is believed to have been once very similar to Earth. In fact, researchers believe that Mars once had rivers and oceans on its surface.
It is thought that the vast amounts of water that once flowed on Mars’ surface washed away, leaving behind evidence of channels and canyons on the Martian surface. This could have caused the formation of the Martian surface that we see today.
At present, no liquid water exists on the surface of Mars because it has a very thin atmosphere. But there are remnants of Mars’ past that still exist on the planet, including sheets of water ice the size of California. These ice caps are located at both of the planet’s poles.
Jupiter
Jupiter is the largest planet in our Solar System, with a diameter about 11 times that of Earth. It is a gas giant, composed of mostly hydrogen and helium. It rotates on its axis faster than any other planet in the Solar System, allowing it to draw its atmosphere into distinct belts that run parallel to its equator.
Jupiter also has the strongest magnetic field of all the planets in the Solar System. This magnetism traps charged particles in an intense belt, blasting its moons and rings with radiation more than 1,000 times the level lethal to a human being.
This ferocious magnetic force makes it impossible for spacecraft to land on Jupiter, since any probe that descends into the atmosphere would be destroyed by the immense pressure. This is why scientists are constantly looking for ways to send spacecraft to Jupiter without destroying them.
Jupiter is also the most frequent planet to receive comet impacts. Its gravity is so strong that it can alter the orbits of a comet, even if it does not eject it from its own orbit entirely. This may be why it has been called the Solar System’s vacuum cleaner.
Saturn
Saturn is the second largest planet in our Solar System. It’s 75 thousand miles (120,000 kilometers) across at its equator, and almost 10 times the diameter of Earth. It’s a gas giant, meaning it doesn’t have a solid surface, but is made mostly of hydrogen and helium.
It also has a strong magnetic field that’s generated by churning metallic hydrogen deep inside. The upper atmosphere of Saturn is characterized by superfast winds, which can reach up to 1,100 mph around the planet’s equator.
The atmosphere is made up of 75% hydrogen, 24% helium and 1% methane, ammonia, and water vapor. It’s also covered with clouds, jet streams and storms.
There’s a hexagonal cloud pattern around the planet’s north pole, and there are strong hurricane-like cyclonic vortices near both the northern and southern poles. The vortices are warm, flow clockwise, and have a central eye that is 2,000 km (1,200 miles) wide.
Like Jupiter, Saturn has a vast array of planet-like moons that are worlds unto themselves. Some of these moons are cratered snowball worlds with rocky cores, while others look like giant sponges or coral reefs.
Uranus
Uranus is the third largest planet, behind Jupiter and Saturn. It is 15882 miles (25,559 km) in diameter and measures a little over 9 times the size of Earth.
Like other gas giants, it has an atmosphere composed mainly of hydrogen and helium with trace amounts of water and ammonia. The atmosphere has a temperature of about -224 degrees Celsius / -371 degrees Fahrenheit.
Its magnetic field is also similar to that of Neptune, with extended weak-field regions, multiple-dip equators and multipolar structure in evidence. It has a bluish appearance due to the presence of methane.
As a result, the surface of Uranus is fairly featureless and uniform. In the interior, it contains a mantle of water, ammonia and methane ices and a core of iron and magnesium silicate.
Like Saturn, Uranus has rings that orbit around its central region. Its outermost rings extend about 75,900 miles (122,200 km) from the planet.
Neptune
Neptune is the fourth largest planet in the solar system. It is almost four times the size of Earth and more massive than Uranus. Its atmosphere is made up of hydrogen, helium, and methane. It also has a small ring system.
Its orbit is tilted 28 degrees from the plane of its orbit around the Sun. This tilt means that Neptune experiences seasons just like we do on Earth.
The atmosphere of Neptune consists of 80% hydrogen and 19% helium. A trace amount of methane is present, with prominent absorption bands at wavelengths above 600 nm in the red and infrared portions of the spectrum.
Temperatures vary with altitude in Neptune’s atmosphere, with a minimum of 50 kelvins (K; -370 degF, -223 degC) occurring at a pressure near 0.1 bar. Above that, the temperature increases to about 750 K (890 degF, 480 degC) at a pressure of a hundred-billionth of a bar.
Neptune’s weather is very active, and dark spots can form in the atmosphere. One such storm was photographed by Voyager 2 when it passed by Neptune in 1989.