Planets may look like stars IN the sky, but they are very different. Stars are huge balls of the hot, glowing gas that create their own light. Planets are big, dark bodies that move around stars. They do not create their own light. Planets shine with the light they reflect from nearby stars. Even though planets are big, stars are much larger than planets. The sun is the nearest star to planet earth.
The largest known star is Vy Canis Majoris. The Sun just looks like the biggest star because it is the closest star to Earth. The Sun is close enough for us to feel its heat
and see its bright light. Other stars are trillions and trillions of miles away. We cannot feel their heat. Most distant stars can be seen only with a telescope. The sun’s volume is more than a million times larger than that of earth.
The Solar System includes not just eight planets and the SUN, but also MOONS, comets, asteroids and dwarf planets. The Sun is at the center. The eight planets — Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune — move or revolve in paths around the Sun. These paths are called orbits. The planets revolve around the Sun at different speeds. The time planet takes to complete an orbit is one year on that planet.
Each planet spins as it goes around the SUN. No two planets spin, or rotate at the same speed. As each planet rotates, the Sun shines on different parts of the planet. It is daytime in the part lit by the Sun. It is night time in the part without sunlight. The time it takes a planet to make a full rotation is one day on that planet.
AN astronaut’s weight would be different ON each planet. It all depends on the pull of gravity. Gravity on the huge planet Jupiter is stronger than on any other planet. An
astronaut who weighs 150 pounds (68 kilograms) on Earth would weigh 355 pounds (161 kilograms) on Jupiter. Mercury is much, much smaller than Jupiter. Its gravity is far weaker. The same astronaut would weigh only 57 pounds (26 kilograms) on Mercury. The sun’s gravity keeps the planets in their orbits.
All planets are made of rock and metals. In some planets, there are also gas and liquids. The four planets closest to the Sun — Mercury, Venus, Earth, and Mars — are all similar.
They are made of rock and metal. But the four planets farthest from the Sun — Jupiter, Saturn, Uranus, and Neptune — are different. Their solid cores are surrounded by huge layers of gas and liquid. The four planets farthest from the sun are called gas planets.