Creation for Kids—Rocky planets
Published in Creation 43(3):34–37, 2021
Besides the sun, the largest objects in our solar system are the eight planets that revolve around the sun. Astronomers group these planets by what they are chiefly composed of: rocky planets, gas giants, and ice giants. The rocky planets are the closest to the sun, the smallest, densest, and the hottest. They are Mercury, Venus, Earth, and Mars. There are many things that make Earth special, so Earth will have its own article. This article will only be looking at Mercury, Venus, and Mars.
Mercury is the closest planet to the sun, and also the smallest of the eight planets. It is ‘tidally locked’, meaning that the sun’s gravity fixes Mercury in a ‘resonance’. That is, it spins three times on its axis for every two revolutions around the sun, or three Mercury ‘days’ for two Mercury ‘years’. This means that there is a huge temperature difference between the ‘day’ side and ‘night’ side. The side that faces the sun is 430 °C (806 °F), around the boiling point of sulfur! But the side that faces away from the sun is a chilly -170 °C (-274 °F), which is around the temperature where oxygen becomes a liquid.
Another reason that Mercury has such huge temperature differences is that Mercury is too small to have an atmosphere. The lack of an atmosphere also means that the sky above Mercury would always be black, like night-time on Earth. But on the daytime side, the sun would be blindingly bright, and take up about seven times more area in Mercury’s sky than it does on Earth.
Venus is often called the ‘morning star’ or ‘evening star’ due to how bright it appears in the sky. It is the brightest natural object in the sky after the sun and moon, but is only visible within about 3 hours of our sunrise and sunset.
Venus is very close to the earth in size. However, its composition is very different. In fact, the compositions of Venus’s atmosphere and surface are very close to how people described Hell in the Middle Ages. Venus’s atmosphere has 93 times the pressure of ours, and is 96.5% carbon dioxide, which is a greenhouse gas. As a result, its surface is hot enough to glow red and melt lead. This means that no organic molecules required for life could ever survive. It is covered with thick clouds that reflect 76% of the sunlight, which is what makes it look so bright.
In 1610, Galileo used a telescope to observe that Venus has phases like the moon. He concluded this meant that Venus orbited the sun, not the earth.
Venus has high mountains—the largest is Maxwell Montes, 11,000 m (36,000 ft) high. The surface also has deep rifts up to 9,000 km (5,600 mi) long.
Mars is reddish because of iron oxide. It’s further away from the sun than Earth, so it is a dry, freezing planet.
Mars has the largest volcano in the solar system by far: Olympus Mons. It is 27 km high, 3 times as high as Mount Everest; and covers an area 300,000 km2 (120,000 sq mi), about the same as Italy. Mars also has the largest canyon in the solar system, Valles Marineris—over 9 times longer than the Grand Canyon!
Interestingly, some scientists think that there was a global Flood on Mars, despite the lack of water today. These same scientists deny that the earth—over 70% covered by water—ever had a global Flood.
Some claimed that Mars had life, because one astronomer claimed to have observed long, straight ‘channels’ on the surface. However, later astronomers as well as high-definition pictures of Mars have shown that these were only optical illusions. There are no artificial structures on Mars.
Could life survive on any of the other rocky planets?
When we look at the other rocky planets, we can appreciate how unique the earth is in supporting life. Mercury is too small and too close to the sun for life. Venus is too poisonous. Mars is too chilly and dry. Only Earth is the right distance from the sun, with enough water and an atmosphere that is composed of the right elements.
The rocky planets clearly show that God specially designed Earth to be a good home for human beings!
Creation question:
Why would God create so many planets if there is only life on earth?
The Bible tells us (Genesis 1:14) why God created the stars and planets! They display His glory, and they are signs and mark seasons for us. Because other planets are so unsuitable for life, we can see how special the earth is. It’s the only place that can be our home.
Science experiment
Find Venus in the night sky! It will be either in the east before sunrise, or in the west after sunset. If you use good binoculars, you might see different phases at different times of year. But look soon after sundown, not when it’s too dark.
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