Sky
Constellation Finder
Look up where any of the 88 constellations sits in your sky, or list every constellation above your horizon right now.
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Constellation, location, and time
All 88 IAU constellations, alphabetical. Type a letter to jump.
-90 to 90, north positive.
-180 to 180, east positive.
Any date from 1900 to 2100.
24-hour clock, your device's time zone.
Where it is in your sky
Right now
Centroid altitude
Azimuth
Best evening month
Crosses the meridian nearest 9 p.m. local mean time.
- Genitive
- Abbreviation
- Brightest star
- Centroid (J2000)
- From your latitude
- Highest it can get
Constellations up now
| Constellation | Well known | Altitude | Direction | Brightest star |
|---|
The 88 constellations at a glance
Every constellation recognised by the International Astronomical Union, with its Latin genitive, official three-letter abbreviation, approximate centroid position (J2000), brightest star, the month it crosses the meridian nearest 9 p.m., and the latitudes it can be seen from.
| Constellation | Genitive | Abbr. | RA | Dec. | Brightest star | Mag. | Best month | Seen from |
|---|
RA and Dec. give the approximate centre of each constellation's official boundary. "Seen from" is the latitude band where that centre can rise above the horizon; edges of large constellations reach further. Serpens is split into two halves (Caput and Cauda), so its single listed centre falls between them, near Ophiuchus.
How this finder works
The tool converts your date and time to Julian Date, computes Greenwich mean sidereal time with the polynomial of Meeus, Astronomical Algorithms, chapter 12 (eq. 12.4), adds your longitude to get local sidereal time, and transforms each constellation centroid's J2000 right ascension and declination to altitude and azimuth with the standard formulas of Meeus chapter 13. Azimuth is measured from north through east. Everything runs in your browser; coordinates from the optional location button never leave the page.
Honest limits: a constellation is a large region of sky, while this tool tracks a single centre point, so a constellation can be partly risen while its centre is below the horizon, and the 20 degree cutoff in the "What is up now" list is indicative, not sharp. Centroids are round-number J2000 positions; ignoring precession, nutation, and refraction shifts them by up to about 1 to 2 degrees at the edges of the supported 1900 to 2100 range, which is negligible against constellation sizes of 10 to 60 degrees. Sidereal time itself is accurate to well under a second. Times are interpreted in your device's time zone, which may differ from the local zone at faraway coordinates, and during a daylight-saving transition an ambiguous wall-clock time is resolved by your browser. The best-month column is computed for the current year at 21:00 local mean time and can shift by one month for observers far east or west in their time zone. Results are for planning and education, not navigation.