September 1
The Square Rises
Sun Position
The Sun sits in Virgo, at a declination of roughly +8°, still north of the celestial equator. In the Northern Hemisphere, days remain noticeably longer than nights; in the Southern Hemisphere, the reverse is already true and days are lengthening toward spring.
Sky Highlight
The Great Square of Pegasus clears the eastern horizon by mid-evening on this date, signaling the full arrival of the autumn sky for Northern Hemisphere observers. Southern Hemisphere observers see it low in the northeast. No major meteor showers peak today.
Deep Sky Object
M15 (NGC 7078), globular Cluster, Pegasus. About 33,600 light-years away, M15 is one of the densest globular clusters known and hosts a rare collapsed core. Northern Hemisphere observers find it well-placed in the southeast after dark; Southern Hemisphere observers can catch it low in the north.
Featured Star
Scheat (β Peg) is a red giant about 196 light-years away with a spectral type of M2.5II-III, cool and luminous enough to pulse visibly in brightness over a roughly 38-day cycle. Look for it as the upper-right corner of the Great Square, slightly ruddy against the surrounding field.
Around This Date
- September 1, 1859Richard Carrington and Richard Hodgson independently observed the first recorded solar flare, a white-light event now called the Carrington Event, which triggered a geomagnetic storm so intense that auroras were seen as far south as Cuba.
- September 3, 1976Viking 2 landed on Mars in Utopia Planitia, becoming the second spacecraft to successfully land on the Martian surface and returning detailed images and soil-analysis data.
The Great Square stands up in the east like a frame with nothing in it yet, give the night an hour and something will fill it.