Astronomy Picture of the Day
apod.nasa.gov
One space image a day, explained by a working astronomer
Cosmos & Scale
Fly out through our stellar neighbourhood, one star at a time
stars.chromeexperiments.com
Instant · Best on desktop
Free, no sign-up · online since 2012
Google's WebGL experiment plots the hundred thousand or so stars nearest the Sun in three dimensions, with the named ones labelled and annotated. Zooming out carries you from the Sun to the local neighbourhood to the whole Milky Way, and a guided tour narrates the trip over a Sam Hulick score.
The zoom never cuts. You pull back continuously from one star to a hundred thousand, and the moment the galaxy resolves around you is the payoff.
Keep going
Picked for a shared category and overlapping vibe, not for popularity.
apod.nasa.gov
One space image a day, explained by a working astronomer
scaleofuniverse.com
Scroll from quantum foam out to the observable universe
spacetelescopelive.org
What Hubble and Webb are pointed at this very minute
sky.esa.int
Search the sky the way the ESA science archives see it
helioviewer.org
The Sun in every wavelength, going back fifteen years
trek.nasa.gov
Fly the whole of Mars on real orbiter mapping data