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Astronomy tutor —
or AI mentor that's free?

Try Mentora before paying $30/hour for a astronomy tutor. Solar System, stars, galaxies, black holes, cosmology. Available 24/7, no schedule, no card.

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Astronomy — a real conversation

How do we know the universe is expanding?
Distant galaxies' spectra are red-shifted. The farther a galaxy, the bigger the shift — meaning they're moving away from us, faster the farther they are. Hubble figured this out in 1929. Want Hubble's law in detail?

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