Mercury is known as an “inferior planet” because its orbit is closer to the Sun than Earth’s. As a result, from our vantage point, it always appears to be facing the same direction as the sun. It is so close to the sun that it can be difficult to spot with the naked eye.Nonetheless, the first three weeks of December will provide us with a wonderful opportunity to see Mercury in the early morning dawn sky. If you’ve never seen this rocky little planet for yourself, now is the best time to do so. So set your alarm for 5:30 AM and go outside to a spot with a clear view of the east-southeast sky.
Best time to see Mercury this December
- On November 20, Mercury was in inferior conjunction with the sun, moving roughly between the sun and Earth.
- Four days later, on November 24, Mercury crossed just one degree north of dazzling Venus, but the pair was only 10 degrees from the sun and appeared about 50 minutes before sunrise, with a magnitude of +2.4. Mercury was still obscured by the dawn’s brilliance.
- On November 27, Mercury rose 75 minutes before the sun and increased its brightness by 3.6 times, reaching magnitude +1.0. It was then rather easy to find, near the east-southeast horizon, approximately one hour before sunrise.
- On December 5, it appeared immediately before morning light in a dark sky and brightened to magnitude -0.3.
Despite being barely 21 degrees from the sun, Mercury experiences an extraordinarily favourable maximum elongation on Sunday, December 7. It will rise in a dark pre-twilight sky around one hour and 50 minutes before the sun, at magnitude -0.4. Only Sirius and Canopus are brighter stars. The 2025 Observer’s Handbook of the Royal Astronomical Society of Canada mentions the best morning appearance of 2025 for Northern Hemisphere watchers.Simply gaze just above the east-southeast horizon 2 hours before sunrise for a beautiful yellowish-orange star.
Mercury easily visible in December: Here’s why
Mercury will be in an excellent position to be seen in the morning sky this month for four reasons:
- For observers in the Northern Hemisphere, the ecliptic, or the apparent path that the sun, moon, and planets follow across the sky over a year, makes a steeper-than-normal angle with the horizon at sunrise in the autumn.
- Mercury is north of the ecliptic for most of December because it passed the ascending node of its orbit on November 18.
- Additionally, because it was closest to the sun on November 23, its orbital speed is almost at its maximum.
- Mercury is significantly closer to Earth and moves more angularly in relation to the sun during inferior conjunction than it does during superior conjunction, when it is on the sun’s far side as viewed from Earth.
By December 7, it will appear to be 62% lighted, and the proportion of its surface illuminated by the sun will continue to increase in the next days. So, while it will begin to spin back toward the sun after December 7, it will brighten somewhat to magnitude -0.5 by December 9, keeping it visible for the following few weeks.
