What kind of star is Lesath?
Lesath, catalogued as Upsilon Scorpii (υ Sco), appears in the official constellation Scorpius. Its apparent visual magnitude is 2.65, while its estimated distance is about 576 light-years. Astronomers classify the object as B2 IV. These labels describe temperature, luminosity class or system components; they should not be read as a claim that every naked-eye point is a single isolated star.
Upsilon Scorpii is a luminous B-type subgiant whose SIMBAD parallax places it near 576 light-years. Its spectral class indicates a massive star beginning to evolve beyond the main sequence. Lesath and Shaula share a similar distance scale and belong to the young Scorpius stellar environment, but their attractive naked-eye pairing is not a tight binary: they are separated by a substantial physical distance. Hot stars like Lesath emit a larger fraction of their energy in ultraviolet light than the Sun, so visual brightness alone understates their total luminosity. The crowded background contains star clusters, dark lanes and emission nebulae toward the Galactic centre, making Lesath a useful foreground marker for wide-field exploration rather than an isolated telescopic object.
The coordinate pair RA 17h 30m 45.84s, Dec −37° 17′ 44.9″ fixes the object's direction on the celestial sphere for the J2000 reference epoch. Right ascension works like celestial longitude measured in hours, while declination works like latitude north or south of the celestial equator. Proper motion and improved measurements can refine catalogue positions, but these coordinates are sufficiently precise for a finder chart or planetarium search.
Lesath data at a glance
| Proper name | Lesath | Catalogue designation | Upsilon Scorpii (υ Sco) |
|---|---|---|---|
| Constellation | Scorpius | Apparent magnitude | 2.65 |
| Spectral or system type | B2 IV | Estimated distance | about 576 light-years |
| Right ascension (J2000) | 17h 30m 45.84s | Declination (J2000) | −37° 17′ 44.9″ |
Values are rounded for an observer-friendly overview. Consult the linked SIMBAD record for component-level identifiers, bibliography, measurement provenance and newer catalogue values.
The name Lesath
The name came through medieval transmission from an Arabic expression associated with a sting or poisonous bite, matching the star's position in the Scorpion's stinger.
Lesath's name was historically entangled with translations of Ptolemy and Arabic star descriptions. Whatever the exact manuscript path, its sting-related interpretation suits the traditional anatomy of Scorpius. The IAU standardized Lesath for Upsilon Scorpii, distinguishing the named star from Shaula even though popular guides group them as the Cat's Eyes. That paired nickname is a modern observing convenience and should not be mistaken for an IAU-approved stellar name.
Modern professional catalogues retain identifiers such as the Bayer designation alongside a proper name. The International Astronomical Union standardizes which name belongs to which component—an important distinction for systems whose combined light looks like one star from Earth.
How to find Lesath
Trace the hook of Scorpius to its eastern end. Lesath is the slightly fainter western member beside Shaula. In binoculars, centre both and then sweep north toward the dense open clusters M6 and M7.
Southern, best on June–August evenings in the north and winter evenings in the south. Visibility on a particular night still depends on latitude, season, time, horizon obstructions, weather and local light pollution. Use the interactive atlas below to check the surrounding field before observing.
Observation checklist
- View in June and July after nightfall.
- Use a southern horizon free of buildings and trees.
- Compare its brightness directly with nearby Shaula.
- Continue a binocular sweep toward M6 and M7.
Interesting facts about Lesath
- Lesath and Shaula form the Cat's Eyes asterism.
- It is a B-type subgiant around 576 light-years away.
- Its name evokes the Scorpion's sting.
- It emits strongly at ultraviolet wavelengths.
- The pair with Shaula is not a close visual binary.
Continue from Lesath into the night sky
Use the Scorpius constellation guide to place this star within its larger pattern. When you are ready to observe, compare dark-sky places, find a nearby observatory, or follow our practical guide to finding a star in the night sky. Symbolically registered names are kept separately in the searchable Star-Register catalogue.
Sources and further reading
Measurements are rounded for readability. Multiple systems, variable stars and distant supergiants can have component-specific or model-dependent values. Survey panels show photographic sky fields, not the physical surface of the star.