And do any other particles escape? And how?
In: Chemistry
Photons have no mass, so they are not captured by Gravity. Other massless particles can escape, as well as regular particles with enough speed. We call the latter “solar wind” and there is quite a bit of it.
You can’t “escape” gravity as gravity has no limit to its range. Its effect simply gets weaker the further away from the source you get. You can move against the (net) pull of gravity by simply applying a force in the direction you want to go. You can try this right now: jump. You just (temporarily) moved against gravity.
Photons, having no mass, are not directly pulled on by gravity but are indirectly affected by it as gravity warps space. But photons move at fast enough speeds that this warping is not sufficient to halt their advance, until you get to things like black holes.
Photons do experience the effects of gravity, but they can escape the sun’s gravity because they are incredibly fast allowing them to keep going even though the sun’s gravity tries to pull them back. More intense gravity (such as a black hole) is so powerful that even a photon‘s speed isn’t enough to overcome it. While photons don’t slow down as they escape the sun’s gravity, they do lose energy which we can measure. This allows us to know what is happening to stars very far away from us.
An object in space has an *escape velocity* based on the mass of that object and how far you are from it.
From its surface, the escape velocity of the Sun is about 618 km/s.
Light travels at 300,000 km/s.
There are also charged particles which do escape the gravitational field. Solar wind, coronal mass ejections, filament eruptions. Through acceleration from magnetic and/or electric fields.
And of course lots of neutrinos.
Every object in the universe distorts what Einstein called ‘spacetime’. If you stretch out a sheet until its taut it’s perfectly flat. Put a marble on it and the marble makes a small depression in the fabric around it. Put a bowling ball on the sheet and the depression and its effects are much much more noticeable than the marble. We call these depressions gravity wells.
Each gravity well has a specific speed needed to escape it. The speed needed to escape from the bowling ball’s depression is much greater than the speed needed than the marble.
Now imagine the bowling ball is the Sun. Photons leaving the sun have more speed than what is needed to escape the sun’s gravity well.
Now imagine you drop a wrecking ball onto the sheet, and the depression it creates is huge. That might be like a black hole, where the speed needed to escape it’s gravity well[1] is much more than even photons have.
[1] This is a wildly over simplification, but it works well enough for ELI5.
At risk of being a bit cheeky:
“With very little issue”.
The sun has by far too little gravity to affect photons themselves in any significant way in the first place. It’s very clearly not a black hole. They just radiate out, no issue.
Same really goes for sufficiently fast particles, they have no trouble flying away from the Sun, and the strong magnetic fields on the Sun’s surface accelerate charged particles, like electrons and protons, well beyond “sufficiently fast”.
Does gravity affect light? Doesn’t it need mass to be effected?
Anything with enough energy can move away from the sun.
The sun’s mass does exert a lot of gravity, so it takes a lot of energy to move away from being close to it.
However, the sun also is a huge source of energy (it is a giant nuclear reactor)! Light, and some other particles, can use some of the energy they gain from the sun’s fusion reactions to move away from the sun.
the sun does not have enough mass to trap photons. even stars that do, can’t because they are not dense enough. their mass is too spread out until they collapse into black holes and form an event horizon. the sun, and all stars, are constantly emitting charged particles and we call that the solar wind. the sun is an explosion in process, and that gives particles enough energy (probably with magnetic field help) to escape the suns gravity.
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