Castor Observation Details
Castor Daily Motion
Castor will be visible until May, 27, when it will move too close to the Sun. During this time, its proximity to the Sun will cause it to disappear from the night sky, making it unobservable for a while.
Castor Visibility Timetable on September 18
Castor Rise and Set Timetable
| Time | Elevation | |
| Moon Rise, 19.7% illuminated | 00:26 | 13° |
| Castor transit | 06:55 | 85° |
| Castor set | 14:47 | |
| Moon Set | 15:21 | -5° |
| Astrosession begin | 18:39 | -21° |
| Castor rise | 22:59 | |
| Astrosession end | 03:24 | 48° |
| Civil sunrise | 04:26 | 60° |
| Sunrise | 04:53 | 65° |
Track Castor Position Throughout the Night
← Thu, 18 September 2025 →
| Time | |
| Altitude | |
| Azimuth |
Shift the map to change the time and observe Castor changing position in the night sky.
Where is Castor right now?
Castor is located in the constellation Gemini, at right ascension 07h 34m 35s" and declination 31° 53' 17s. Although it is currently above the horizon at an altitude of 30 degrees, Castor is not visible because it is daytime.Castor - Multiple Star System
Castor is the second-brightest star in the constellation Gemini and the twenty-fourth-brightest star in the night sky. It is a multiple star system located about 51 light-years away from Earth.
Castor has an apparent magnitude of 1.58 and consists of six main stars. It is one of the most prominent stars in the winter sky in the Northern Hemisphere.
Finder Chart for Castor
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| Object name | Castor |
| Field of view | |
| Limiting magnitude | |
| Castor coordinates | 7.576633999999999, 31.888276 |
| Center coordinates | 7.576633999999999, 31.888276 |
Castor Passage Through Night
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Current position of Castor
| Time | 11:53 |
| Latitude | 37.3541 |
| Longitude | -121.955 |
| Castor elevation | 30° |
| Castor Azimuth | 71° |
Here you can see the current position of the Castor on the map, as well as its positions for rise and set. This tool allows you to track the Castor's movement throughout the night, providing you with accurate and up-to-date information.
Annual motion of Castor
| Date | Thu, 18 September 2025 |
| Twighlight start | 18:35 |
| Twighlight end | 03:18 |
| Twighlight duration | 9h 43m |
| Rise | 22:59 |
| Set | 14:43 |
| Elevation at transit | 85° |
| Transit time | 06:51 |
| Equatorial coordinates | RA: 07h 34m 35s", Dec: 31° 53' 17s |
| Magnitude | 2 |
| Constellation | Gemini |
The graph illustrates the annual visibility pattern of a Castor, providing a comprehensive overview of its daily appearances and transit times throughout the year.
The graph is structured with the vertical axis showing the hours of the day, ranging from 12 AM to 12 AM the next day, while the horizontal axis spans each day of the year.
The reddish shaded area indicates the periods when the Castor is above the horizon, visible to observers. The white line marks the times when the celestial object reaches its highest point in the sky each day, known as the transit.
The graph is structured with the vertical axis showing the hours of the day, ranging from 12 AM to 12 AM the next day, while the horizontal axis spans each day of the year.
The reddish shaded area indicates the periods when the Castor is above the horizon, visible to observers. The white line marks the times when the celestial object reaches its highest point in the sky each day, known as the transit.
Astrometric & Physical Parameters of Castor
Coordinates & Visibility
| Right Ascension | 7.576633999999999° |
| Declination | 31.888276° |
| Magnitude | 1.58 |
| Constellation | Gemini |
| Elevation | 29.9° |
| Azimuth | 70.9° |