Galaxies are formed by stars, planets, comets, meteors, and other space bodies.
Stars have their own source of energy, tones of hydrogen burned into hellyum every second, while planets don't have, and get heat from the nearest star. Stars are the furnace of the universe eventually allowing planets to develop life, like the Earth.
Stars emit all kinds of radiation, planets don't. This is why:
Stars are made mainly of Hydrogen. Planets are made mainly of heavier elements.
Stars have lot of Hydrogen and big mass. Big mass produces strong gravity force (which raises pressure) and it raises temperature inside the star. High temperature and pressure ignite atomic reaction called Nuclear Fusion, combining Hydrogen atoms into Helium atoms. (Hydrogen bomb works the same way.) Fusion releases energy and stars emit their own radiation, including heat, visible light, UV rays, X-rays, Gamma rays... and atomic and sub-atomic particles. Released Fusion energy also speeds up the further Fusion.
Planets are smaller and their mass (and gravity and pressure) is lot lower. They have no atomic reactions and they don't emit their own radiation. We can see them when they reflect star light.
Stars are made up of primarily hydrogen, with some helium and a tiny bit of other elements mixed in. They generate energy in their cores through nuclear fusion, combining hydrogen nuclei into helium nuclei, and converting some of the matter into energy. Our Sun is a perfectly ordinary star, which seems so large and hot because it is the closest star to us.
Planets are made of all kinds of matter, and most planets are a tiny fraction as large as any star. Our Earth is a planet, made up of hydrogen, oxygen, iron, and all the other elements, but while the Sun is mostly hydrogen, the Earth is primarily rock and iron with some hydrogen and oxygen mixed together as water on the outside.
Some planets like Jupiter are more gaseous, containing more hydrogen and other gasses like ammonia, nitrogen and others.
The Sun is about 1 million times heavier and 1,000 times bigger than the Earth. In fact, the Sun is about 99.8% of all the mass in our solar system. (Most of the rest is Jupiter.)
The difference is that the sun is a star, the other planets are just planets
A galaxy contains planets and a star system contains only stars.
Basically, Earth is a planet, the Sun is a star, and a comet is an icy small body of ice.
The planets inside the steroid belt will get hit and the other planets will not.
Extra solar (or Exo) planets are planets that do not orbit the Sun. Planets in our solar system orbit the Sun.
Extra solar (or Exo) planets are planets that do not orbit the Sun. Planets in our solar system orbit the Sun.
life
Inner planets are mostly rock and outer planets are mostly gas.
No. That's precisely the main difference between planets and stars - that stars can have nuclear fusion, planets not.
a difference will be the prices.
Planets do not twinkle.
yes, planets do orbit a star