Asterank
asterank.com
Which asteroids would pay for the trip out to reach them
Cosmos & Scale
The sky atlas professional astronomers use, in a tab
aladin.cds.unistra.fr
Coffee break · Best on desktop
Free, no sign-up · online since 2013
Aladin Lite is the browser version of the atlas maintained by the Strasbourg astronomical data centre. It streams tiled survey imagery at any zoom level and overlays catalogue entries and published measurements on top, which is how objects in a paper get checked against the real sky.
It is the same tool cited in research papers, so you can paste a coordinate from a preprint and see precisely what the authors were pointing at.
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Picked for a shared category and overlapping vibe, not for popularity.
asterank.com
Which asteroids would pay for the trip out to reach them
sky.esa.int
Search the sky the way the ESA science archives see it
zooniverse.org
Classify a galaxy nobody has ever properly looked at
helioviewer.org
The Sun in every wavelength, going back fifteen years
joshworth.com
A map of the solar system with the empty space left in
trek.nasa.gov
Fly the whole of Mars on real orbiter mapping data