Lesath (Upsilon Scorpii)
Lesath (Upsilon Scorpii) is a star in the constellation Scorpius, magnitude 2.6.
One of the Scorpion’s two stinger stars — with a name born of a scholar’s mistake.
Lesath’s name is a scholar’s mistake. The Arabic las‘a, “the bite of a poisonous animal”, suits a star in a scorpion’s sting — but it was a miscorrection by Scaliger, a European astronomer who knew Arabic. The earlier name, Alascha, came from al-laṭkha, “the foggy patch”: the star cluster M 7 nearby.
With brighter Shaula, it has been a pair in many skies. The Babylonian star list MUL.APIN names the two as Sharur and Shargaz; in Coptic they were Minamref; and the Boorong people of north-western Victoria saw them as Karik Karik, the Falcons.
The star itself is a hot blue-white subgiant of about 11 times the Sun’s mass and six times its width, with a surface near 23,000 K. It gives out some 12,000 times as much light as the Sun.
Lesath (Upsilon Scorpii) is 580 light-years away: the light we see from it set off around 1445, around the time Gutenberg printed his Bible.
Did you know?
- Ninth star of the Tail. In Chinese astronomy Lesath is the ninth star of Wěi, the Tail — the long curl of stars that forms the Scorpion’s tail.
- USS Lesuth. A US Navy Crater-class cargo ship, USS Lesuth (AK-125), was named after the star, using one of its older spellings.
A blue-white star of magnitude 2.7 at the tip of the Scorpion’s tail, just beside brighter Shaula; together they are called the Cat’s Eyes. The open cluster M 7 lies about 5 degrees to the north-east — a fine sight in binoculars.
When and where to see it
It is best placed in the evening sky around July, when it crosses the meridian at about 10 pm local time (around midnight in June). It can be seen from everywhere south of 53°N and never sets south of 53°S.
At its highest it stands 3° up from 50°N, 18° up from 35°N, 53° up from the equator, 88° up from 35°S.
Facts
- Type
- Star
- Constellation
- Scorpius
- Designations
- Upsilon Scorpii, υ Sco, 34 Sco, HR 6508, HD 158408, HIP 85696
- Magnitude
- 2.6
- Position
- RA 17h 30.8m, Dec −37° 18′ (J2000)
- Spectral type
- B2IV
- Colour
- blue-white (B−V -0.17)
- Distance
- 580 light-years
- Discovered
- Known since antiquity
Open AstroPilot to see when Lesath (Upsilon Scorpii) is highest tonight from your location, how easy it is with your telescope or binoculars, and an eyepiece view.