SpaceNerd vs Astrelia

SpaceNerd helps you recognize what you’re pointing at in the sky and learn to navigate by stars, planets, and deep-sky objects — using your iPhone’s motion sensors and approximate location. Modes • What (Identity): aim at a star or planet to identify likely matches. • Where (Guidance): pick a star, planet, or deep-sky object and get live azimuth/altitude guidance to find it. If the object is not in the built-in catalog, SpaceNerd can look it up through SIMBAD. • Const (Constellations): search a constellation and use a guide star to point at it. • Game: race to find a target star — timer stops when you lock on the star. Tip: Tap “?” in the top-right corner anytime for quick help and instructions. How it works SpaceNerd uses the device’s motion sensors and your approximate location to estimate where you’re pointing, then compares that direction to a catalog of stars, planets, constellations, and selected online astronomical object data. It doesn’t require stars to be visible on the camera image — so it can still be useful in daylight, through thin clouds, or even indoors for learning and practice. For best accuracy, move slowly and use it outdoors with a clear view of the sky. Privacy No account required. No ads. No analytics or tracking. Location is used on-device to compute sky positions and is not stored or shared. Data sources Planet positions are based on NASA/JPL ephemerides. The built-in star catalog was compiled offline using SIMBAD for RA/Dec references and Stellarium for constellation asterisms. Expanded Where searches may query SIMBAD, operated by CDS, for astronomical object lookup. Wikipedia may be opened when you tap “Open Wikipedia.”

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.