Why do stars have different colours?



Stars all look the same colour, don’t they? That’s true if you see them with the naked eye. Through a telescope the picture changes. Once you look at stars when they are magnified, you see that they all have different colours.



Surface temperature controls the colour of a star. Our most familiar one is the sun. That has a surface temperature of around 5000  and is yellow-white in colour. There are plenty of stars in the universe far hotter than the sun. The hottest are twice as hot on the surface, and these are blue. Surprisingly, red stars are the coolest ones. The surface temperature on these is about 3000 . Knowing this, scientists are able to estimate the surface temperature of stars by carefully measuring their colours.



 



Picture Credit : Google


What are the Planets of the solar system?


The Solar System



Our solar system contains the sun and the many objects that travel around it. Some are planets much larger than Earth. Others are tiny meteors and bits of dust.



The Sun’s Family



There are nine planets in our solar system. Each of them moves around the sun in a certain path. This path is called an orbit.



The first two planets, Mercury and Venus, are very close to the sun. The others are much further away. Two planets are much smaller than Earth. One is about the same size. And four are much bigger.



Like Earth and the moon, the other planets in our solar system reflect the sun’s light. That’s why we can see some of them at night.



The sun’s family also includes objects called asteroids, comets, dwarf planets, and meteoroids. Asteroids are small masses of rock or metal. Most of them move around the sun between the orbits of Mars and Jupiter.



Comets are frozen balls of ice, gas, and dust that travel around the sun. Comets have long shining tails.



Dwarf planets are small, nearly planet-sized objects that travel around the sun. Many dwarf planets are in the Kuiper belt, a region of space just beyond Neptune.



Meteoroids are chunks of rock or metal that move through space. When a meteoroid enters Earth’s atmosphere from outer space and begins to burn, it becomes a bright streak called a shooting star, or meteor.



Picture Credit : Google


What are the nicknames of planets?



Mercury - Swift Planet



Because it moves quickly around the Sun and circles it faster than all the other planets.



Venus - Morning and Evening Star



The two nicknames given to Venus are because it rises and sets each day, like the Sun. It is visible from Earth, like a star in the sky, in the morning before the Sun rises, and in the evening as soon as the Sun sets.



 



Earth - Blue Planet



Most of the Earth is filled with water, and this makes the planet appear blue from space.



Mars - Red Planet



Mars is nicknamed so because it appears in the sky as an orange-red star. Toray, scientists know that Mars appears so due to the net on the Martian rocks.



Jupiter - Giant Planet / Gas Giant



Jupiter is the largest planet in the solar system. In fact, it is so big that all the other planets in the solar system could fit inside it! It is also known as the Gas Giant because its atmosphere is mostly made up of hydrogen and helium gas just like the Sun.



Saturn - Ringed Planet



Saturn is known so because of its rings. The other gas giants in the solar system, such as Jupiter, Uranus and Neptune also have rings, but only Saturn’s are visible prominently.



Uranus - Sideways Planet / Bulls Eye Planet / Ice Giant



Uranus is four times the size of the Earth ant is the coldest planet in the solar system. Hence, it is called the le Giant. It is known as the Sideways Planet because it rotates on its side. And, as for the nickname Bulls-Eye Planet, it is because Uranus’ rings are vertical, unlike Saturn's which are horizontal. This makes it appear like a bulls-eye on a target.



Neptune - Big Blue Planet / Windy Planet



Neptune looks blue from space, just like Earth, but i many times larger than our planet. Hence it is called the Big Blue Planet. It is sometimes also called the Windy Planet because winds in Neptune can whip clouds of frozen methane at speeds of more than 2.000 km/h!



 



Picture Credit : Google


Do all the planets and their moons have active volcanoes?



For many years, scientists believed that Jupiter's moon lo was geologically dead. This means it didn't have things such as earthquakes, newly forming mountains or volcanoes. However, it turns out the scientists were wrong about lo. In 1979, when NASA's Voyager 1 spacecraft took close up pictures of lo, the pictures showed a massive plume erupting from lo's surface into space. That's when they realise that lo did not just have volcanoes, it had active volcanoes. And, lo was no longer considered geologically dead. When these pictures were taken it was the first time an erupting volcano was found anywhere other than Earth. So that leaves us wondering, do all the planets and their moons have active volcanoes? Let's take a look



Mercury: The planet once had active volcanoes, but not anymore. Scientists believe violent volcanic eruptions that shaped Mercury's surface, likely ended about 3.5 billion years ago.



Venus: Venus, on the other hand is covered with volcanoes. The hottest planet in our solar system has over 1,000 volcanoes, including some that might still be active, according to what scientists think.



Mars: Mars is home to Olympus Mons, the solar largest volcano in our system. It is also the mountain in our solar largest led our solar system Mars is filled with tall volcanic mountains, and while scientists haven't seen an eruption on Mars, they think there could be some in the future.



Jupiter: Scientists have found volcanoes and observed volcanic activity only on lo, Jupiter’s moon. Eruptions from lo's volcanoes are so massive that it can been seen by a spacecraft that is pretty far from lo.



Saturn: Saturn's moon Enceladus has cryovolcanoes. These volcanoes are similar to regular volcanoes, except they spew water and other gases like geysers.



Uranus: Since it is a gas planet, it does not have any volcanoes.



Neptune: While Neptune doesn't have volcanoes as it is a gas planet, its frozen moon, Triton, has cryovolcanoes that are active.



 



Picture Credit : Google