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April 7: Comet C/2025 R3 (PanSTARRS) enters the scene
Before we lose sight of Canis Major in the nighttime sky, get in a last good look at the Big Dog’s famous double star, 145 Canis Majoris, sometimes called the Winter Albireo.
Two hours after sunset, once the sky is dark, find Canis Major’s bright star, Sirius — the brightest star in the sky — some 20° above the southwestern horizon, to the left of Orion’s Belt. Sirius typically represents the front end or nose of the Big Dog; over above his back, near his tail, is where we’re looking tonight. From Sirius, slide your telescope about 10° to the left (southeast), keeping it at the same height above the horizon. There, about 3.6° north-northeast of Wezen (Delta [δ] CMa), lies 145 CMa.
This lovely pair is separated by just over 25”, making both stars easy to spot in many scopes. If Antares’ companion was a challenge the other night, this will be a much easier and more rewarding target. Like Antares and Albireo, the star that lends this pair its nickname, the two suns of 145 CMa have contrasting colors, appearing orange and blue.
The “real” Albireo, which lies in Cygnus and is cataloged as Beta Cygni, is a staple of the summertime sky. Once it’s visible in the evening in a few months, make sure to visit it and compare the view.
Sunrise: 6:32 A.M.
Sunset: 7:32 P.M.
Moonrise: 1:30 A.M.
Moonset: 10:12 A.M.
Moon Phase: Waning gibbous (60%)
*Times for sunrise, sunset, moonrise, and moonset are given in local time from 40° N 90° W. The Moon’s illumination is given at 10 P.M. local time from the same location.
