Buying Guides
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Best Binoviewers
Look through your telescope with both eyes for sharper, more relaxed views.
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Best Telescopes for Adults
Serious scopes for grown-up stargazers, from first purchase to upgrade.
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Best Telescopes Under $200
Where budget scopes start showing planets and bright galaxies well.
Free Resources
Space Printables
Free PDF quizzes and worksheets for kindergarten to adult, with answer keys.
3D Space Models
Spin real maps of the Moon and planets built from NASA data. Find craters, landing sites, the rings of Saturn, Uranus and Neptune and the moons of Jupiter.
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On August 15, 1977, a radio telescope in Ohio recorded 72 seconds of a narrow, powerful signal near the hydrogen…
Around 105 women have flown to space. Out of everyone who has ever left the planet, that’s fewer than 15%.…
Gravitational lensing happens when matter sits between a distant light source and you, and its gravity bends the light on…
Contents TLDR: which planetarium should you visit? Arkansas has few planetariums, and fewer of them take walk-ins. Here is the…
TLDR Table of contents Canada has a small astronomy community and a long list of results that people outside Canada…
Contents What is a binary star? A binary star is a pair of stars held together by gravity, each orbiting…
A neutron star is the collapsed core of a massive star that blew up as a supernova: about 1.4 times…
TLDR Table of contents What is an ocean planet? An ocean planet is a planet or moon with a global…
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