How to create 2D glowing effect

Hi, how would I go about creating this sort of 2d glowing effect, you see around planet or the asteroids.


Tried to google it, but no luck finding any explanation.
Not sure whether this is done only with shader, or generated texture or some gl points/lines with decreasing alpha.

I`m openGl beginner, so pls go easy on me.
Thanks for any help.

It’s most likely a sprite with partial alpha. Possibly using additive blending (as the order doesn’t matter if multiple effects overlap).

But how do I shape the sprites alpha to exact nice looking glows around stuff? And the shape doesnt have to be nice circle, it can be curved etc.