How do you figure out how fast something is moving, what direction it is moving in, and where exactly it will be at any given time in the future when all you have to go on is pictures? I’m especially wondering about exoplanets and asteroids, the best pictures of those we can get are practically pixels. I don’t understand how we can measure mass, velocity, and orbits from that.
In: Physics
They do it by taking as many pictures as they can over time and feed the data into computers that are programmed to calculate orbital trajectories. Asteroids aren’t that hard if you can get a few good looks at them. If you get an image of the same asteroid every two weeks for six months, you have plenty of data to calculate an orbit. Exoplanets are a bit different – transit times across the face of distant stars coupled with a star’s wobble provide data points to calculate certain features of the exoplanet. Also, while something may be blurred out in a visual image, it may be crisper in an X-ray observation (or other non-visual imaging system), allowing more detail to be known.
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