Planets TonightMercury in 1991: brightness, position and events
Brightest-2.1around Jun 15
Closest (in table)0.580 au87 million km
Farthest1.417 au
Events this year13
Brightest last year-2.2
Events this year
| Date (JST) | Event | Mag | Dist (au) | Constellation | Elong. |
|---|---|---|---|---|---|
| 1991-01-14 18:06 | Greatest western elongation (morning) | -0.2 | 1.012 | Sagittarius | 23.7° |
| 1991-03-02 11:35 | Superior conjunction | -1.8 | 1.369 | Aquarius | 1.8° |
| 1991-03-27 23:45 | Greatest eastern elongation (evening) | -0.1 | 0.894 | Pisces | 18.8° |
| 1991-04-15 05:42 | Inferior conjunction | +6.5 | 0.581 | Pisces | 2.1° |
| 1991-05-13 02:56 | Greatest western elongation (morning) | +0.5 | 0.826 | Pisces | 26.2° |
| 1991-06-17 13:37 | Superior conjunction | -2.4 | 1.323 | Taurus | 1.0° |
| 1991-07-25 11:10 | Greatest eastern elongation (evening) | +0.5 | 0.862 | Leo | 27.0° |
| 1991-08-22 05:41 | Inferior conjunction | +5.4 | 0.619 | Leo | 4.4° |
| 1991-09-08 02:43 | Greatest western elongation (morning) | -0.2 | 0.931 | Leo | 18.0° |
| 1991-10-04 01:39 | Superior conjunction | -1.7 | 1.402 | Virgo | 1.2° |
| 1991-11-19 10:59 | Greatest eastern elongation (evening) | -0.2 | 1.018 | Ophiuchus | 22.4° |
| 1991-12-08 23:57 | Inferior conjunction | +6.2 | 0.678 | Ophiuchus | 1.5° |
| 1991-12-28 05:25 | Greatest western elongation (morning) | -0.3 | 1.016 | Ophiuchus | 22.2° |
Magnitude through the year (lower = brighter)
Twice-monthly position and visibility
| Date | Mag | Dist (au) | Constellation | Elong. | Visibility |
|---|---|---|---|---|---|
| Jan 1 | +0.8 | 0.749 | Ophiuchus | 16° W | Morning sky |
| Jan 15 | -0.2 | 1.026 | Sagittarius | 24° W | Morning sky |
| Feb 1 | -0.3 | 1.271 | Sagittarius | 19° W | Morning sky |
| Feb 15 | -0.7 | 1.372 | Capricornus | 12° W | Too close to the Sun |
| Mar 1 | -1.7 | 1.374 | Aquarius | 2° W | Too close to the Sun |
| Mar 15 | -1.3 | 1.208 | Pisces | 12° E | Too close to the Sun |
| Apr 1 | +0.6 | 0.781 | Pisces | 18° E | Evening sky |
| Apr 15 | +6.5 | 0.580 | Pisces | 2° W | Too close to the Sun |
| May 1 | +1.3 | 0.661 | Pisces | 22° W | Morning sky |
| May 15 | +0.4 | 0.865 | Pisces | 26° W | Morning sky |
| Jun 1 | -0.6 | 1.157 | Aries | 18° W | Morning sky |
| Jun 15 | -2.1 | 1.319 | Taurus | 3° W | Too close to the Sun |
| Jul 1 | -0.8 | 1.220 | Gemini | 16° E | Evening sky |
| Jul 15 | +0.1 | 1.013 | Cancer | 25° E | Evening sky |
| Aug 1 | +0.7 | 0.762 | Leo | 26° E | Evening sky |
| Aug 15 | +3.0 | 0.620 | Sextans | 13° E | Too close to the Sun |
| Sep 1 | +1.1 | 0.762 | Leo | 15° W | Morning sky |
| Sep 15 | -1.0 | 1.132 | Leo | 15° W | Morning sky |
| Oct 1 | -1.6 | 1.386 | Virgo | 2° W | Too close to the Sun |
| Oct 15 | -0.8 | 1.417 | Virgo | 8° E | Too close to the Sun |
| Nov 1 | -0.4 | 1.305 | Libra | 17° E | Evening sky |
| Nov 15 | -0.3 | 1.097 | Scorpius | 22° E | Evening sky |
| Dec 1 | +0.9 | 0.757 | Ophiuchus | 15° E | Evening sky |
| Dec 15 | +1.2 | 0.742 | Ophiuchus | 14° W | Too close to the Sun |
Computed with the JPL DE421 ephemeris and Skyfield (times in JST). Magnitude and distance are for 12:00 JST on each date. Visibility is a rough guide for mid-northern latitudes such as Japan.
About this page
Mercury is brightest around June 1991 (magnitude -2.1); 13 conjunctions, oppositions or elongations occur this year.