APOD Explorer vs Astrelia

Every day, NASA publishes a new astronomy picture or video, with an explanation written by a professional astronomer. APOD Explorer brings it to you with an experience built for exploring the universe, not just looking at it. THE FULL ARCHIVE SINCE 1995 Over 11,000 photos and videos, from the very first APOD to today. Full-text search across titles and explanations, curated tag collections (galaxies, nebulae, eclipses, Earth from space, and many more), and an "On This Day" section showing what was published on this date across the years. READINGS TAILORED TO YOU, ON DEVICE With Apple Intelligence, every explanation can be generated at different reading levels: quick, general, for kids, or for experts. NASA's original explanation can also be translated right on your device — nothing is sent to any server. FAVORITES THAT SYNC Save the photos you love and access them from any of your devices through iCloud. No one else can see them. WIDGETS AND LOCK SCREEN Two widgets — "Picture of the Day" and "Today's Sky" — that refresh themselves every morning, on the Lock Screen too. SHARE WHAT YOU DISCOVER Share the photo or, when the day's APOD is a video, a poster generated from it, straight from the detail view or from the widgets extension. NO ACCOUNTS, NO ADS, NO TRACKING APOD Explorer doesn't require sign-up and doesn't show ads. If you enjoy the app, you can leave a voluntary tip from Settings — a gesture of support that never unlocks features. A daily window into the universe, with NASA's complete archive always in your pocket.

Raise your phone toward the sky and Astrelia shows you what is actually up there: stars, planets, the Moon and the Sun, placed for your exact location and this exact instant. Tap anything and it tells you everything it knows. POINT AT THE SKY Around 8,900 naked-eye stars, sized and coloured the way the eye sees them. Constellation lines, the ecliptic with the live planets, and a Sun and Moon computed with topocentric parallax and atmospheric refraction, so they sit where you can genuinely see them. Pinch to zoom and more names appear. Tap any star to identify it. Scrub time twelve hours forward or back and watch the whole sky move. Aim at something bright and align, and the compass error that ruins most sky apps is cancelled out. TONIGHT One screen for what is happening: the Moon's phase, sunrise and sunset, which planets are up right now and which are below the horizon, meteor showers near their peak, and what is coming — eclipses, oppositions, solstices, greatest elongations. All of it searched out of the live ephemeris, not read from a hardcoded list. NUMBERS THAT MEAN SOMETHING Every object opens into real astrophysics: distance, spectral class, temperature, luminosity, derived radius, orbital elements. Next to them, plain language — the year the light you are looking at left that star, how many Suns it would take to match it, what you would weigh on that planet, where the star falls on the HR diagram, and a one-line biography of its life. Anything unfamiliar has a glossary entry a tap away. THE GALAXY MAP Leave Earth entirely and free-fly a 3D map built from real data: about 25,000 catalogued stars at their true distances, the Milky Way as its real barred spiral, and deep-sky landmarks at their real positions, distances and sizes. Twenty-seven nebulae are built from public-domain telescope photographs, so their shape and colour are the ones the telescope saw — fly into them and they hold up in three dimensions. Fly to a star and its confirmed exoplanets are there, orbiting it. At the galactic centre, Sagittarius A* is rendered by tracing light through curved spacetime: the galaxy behind it genuinely bends around it. CONSTELLATIONS All 88 IAU constellations, plus asterisms, historical figures and cultural skies, each drawn over its real stars. Open any of them in 3D and the familiar shape falls apart into deep space, because a constellation is a line of sight rather than a thing. Astrelia computes all of it on your device from catalogs that ship inside the app. No account, no subscription, no ads, no tracking, and no network needed to use it. Every dataset, algorithm and image behind it is credited in About → Sources. Astrelia has a sister app, Selenia, which reads the same real sky the astrological way.