Almanac · Planets
Mercury and Saturn 2.0° apart, 10 Apr 2025
Mercury and Saturn passed 2.0° apart on Thu 10 Apr 2025 at 13:42 UTC, 25° west of the Sun in the morning sky: close enough to read as one pair, and to share a binocular field. The next is Mercury and Saturn 34′ apart, 19 Apr 2027.
- Closest In the morning sky, low in the east before sunrise
- Brightness Mercury +1.0, Saturn +1.1 Magnitude: lower is brighter; the brightest stars are near 0
- Apart 2.0° 25° west of the Sun
Latitude by latitude
At each latitude, the moment within 12 hours of the event, with the Sun at least 6° below the horizon, that the lower of the two planets stands highest, and how high. Times are local solar time: your clock may differ by up to an hour or two, by your time zone.
| Latitude | Best moment | The Sun then | What you see |
|---|---|---|---|
| 60°N | — | — | The pair is below the horizon whenever the sky is dark |
| 45°N | 04:52 | 6° down | Lost in the horizon's haze: 1° up at best once it is dark |
| 30°N | 05:12 | 6° down | Low: 7° up in the E at 05:12; a clear, flat horizon needed |
| 15°N | 05:22 | 7° down | 11° up in the E at 05:22 |
| 0° | 05:32 | 7° down | 14° up in the E at 05:32 |
| 15°S | 05:42 | 7° down | 17° up in the E at 05:42 |
| 30°S | 05:42 | 8° down | 15° up in the E at 05:42 |
| 45°S | 05:52 | 7° down | 15° up in the ENE at 05:52 |
How we worked it out: the planets are placed by VSOP87, the planetary theory the map draws, within about an arcsecond of JPL’s ephemeris, and the Sun by Meeus’s solar theory. The conjunction is the instant of closest approach, found to the second, which is what most calendars mean by one; the instant the two share a right ascension can be hours away. Pairings within 3° are listed only where some latitude has them at least 3° up after dusk. Each latitude is walked every 10 minutes over the 12 hours either side, at Greenwich’s longitude. The tests hold the dates to the U.S. Naval Observatory’s and the published calendars’, within a day, and the angles within 0.3°.
- P. Bretagnon and G. Francou, VSOP87, the planetary theory the map draws, held to JPL’s DE441 within about an arcsecond over 1900–2100
- U.S. Naval Observatory and Sea and Sky’s Astronomy Calendar of Celestial Events: the dates and angles the tests hold these to
- A. Mallama and J. Hilton (2018) and the Astronomical Almanac’s phase-angle series: the planets’ magnitudes
- J. Meeus, Astronomical Algorithms, ch. 25: the Sun, for the twilight each latitude is judged in