Planets and Stars

Planets and stars are, honestly, some of the most fascinating things in the universe; we can’t really get bored of looking up. They are part of what gives the night sky that beauty and weirdly complex look we see almost every day. Also, planets and stars help us understand the structure and how the universe evolves, not just in a general way but in a sort of step-by-step sense. In this essay, we are going to look at the traits of planets and stars and also at how they fit into the bigger universe picture.  

Planets are celestial bodies that orbit a star, and they don’t produce light by themselves. In our solar system, there are eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Each one has its own particular qualities that make it different, in a way that feels almost personal. Mercury is the tiniest planet, and it is the closest to the Sun, while Neptune is the farthest out and also the coldest. Venus, meanwhile, is considered the hottest planet, with surface temperatures that go above 450 degrees Celsius, which is pretty intense.  

The making of planets starts with a nebula, basically a cloud of gas and dust out in space. Over time, the nebula collapses because of gravity, and then, at the centre, it turns into a protostar. And from there, everything else kind of continues, like slowly, but for real.

As the protostar gets hotter and denser, it kind of starts to radiate light and energy. Meanwhile, the leftover gas and dust in the nebula… it all begins to clump up together, not perfectly neatly though, into smaller solid bits often called planetesimals. Then these planetesimals bump into each other and stick, again and again, until they become the solid cores of planets. Gradually the cores get bigger, and they start pulling in more gas and dust so that the planet atmospheres build up over time.

Stars, though, are different. They are huge luminous celestial bodies that make their own light and energy, mainly by nuclear fusion. In a way, stars are made by the same overall kind of process as planets, but they need a far larger quantity of gas and dust, enough to create the gravitational forces that really kick in. The most typical kind of star is a main-sequence star, which includes our own Sun. For a main-sequence star, hydrogen atoms get fused into helium right in the core, and that fusion releases enormous energy as it goes.

Stars seem to show up in a bunch of sizes and hues; it kind of depends on how much mass they started with and also how long they’ve been around. The biggest ones are usually called supergiants, and yeah, they can end up being thousands of times larger than our Sun. Supergiants are also among the most brilliant stars; they spill out huge amounts of energy, so much so that we can spot them from really far away. Red giants are stars that have already used up their hydrogen supplies; then they start fusing helium instead. While they’re doing that, they expand outward and cool down, so they shift into that red colour. Then there are white dwarfs, which are basically what’s left over after a star has run out of fuel entirely and it collapses because of its own gravity. They’re extremely dense and also very small, with a mass close to the Sun, but a radius roughly comparable to Earth. 

Also, stars are not really still; they are constantly evolving during their entire lifespan. When a star works through its fuel, it doesn’t just “stay the same"; it slowly alters its size, surface temperature, and luminosity. After it uses everything, it may end up in a supernova explosion, and that is one of the strongest events in the cosmos. Supernovae dump out staggering quantities of energy, enough to be seen from distant places, and in some cases they can even appear in daylight from Earth. In a way, planets and stars have this sort of mutual influence; they affect each other’s growth and how everything keeps unfolding over time.

Planets are made using basically the same stuff as stars, and what they’re made of depends on the kind of star they’re hanging around with. How far a planet is from its star ends up setting its temperature, and that temperature basically decides what kind of air it has and what its surface looks like. Like, if a planet is too close, it might be way too hot, so there’s not much room for life, but if it’s too far out, it can get overly cold instead. Stars also make a big difference in how planets grow, partly because of radiation that leaks out and those solar winds that just keep coming. Star radiation can peel off a planet’s atmosphere little by little over time, and solar winds can grind down the planet’s surface. Still, stars can also shelter planets from