Mercury reaches its greatest western elongation from the Sun on November 20, 2026. This is its best viewing window in the fall mornings. Low in the east before dawn, the fleeting planet can be seen with the naked eye if the horizon is clear. But behind this bright spot lies a surprising planet: some astrophotographers have managed to capture its sodium tail, which stretches 2.5 million kilometers long.
Mercury is the hardest planet to see in the solar system. Not because it is faint, but because it never strays very far from the Sun. On November 20, 2026, it reaches its greatest western elongation: about 19° west of the Sun. This is a morning elongation: Mercury rises before the Sun.
The viewing window is narrow. 30 to 45 minutes before sunrise, look low in the east-southeast. The sky is beginning to brighten, but Mercury is still visible. Too early: Mercury is too low. Too late: the Sun drowns it out with its brilliance.
From Switzerland (latitude 46–47° N), Mercury reaches an altitude of about 10–15° above the horizon at the optimal viewing time. This is better than the eastern elongation in October (8–10°), because in November the ecliptic forms a wider angle with the eastern horizon. But it’s still low: a tree, a building, or a hill to the east-southeast is enough to block it from view. Choose a clear horizon.
Look for a bright, pinkish-white point of light that shines brighter than the surrounding stars. At magnitude -0.4, Mercury is brighter than most stars visible to the naked eye. But it is low on the horizon, where atmospheric refraction and haze make it harder to see.
Through 10×50 binoculars: Mercury appears as a bright point, not as a disk. This is enough to locate it and confirm its presence. Through a 70 mm+ telescope at 50x–100x magnification: a small disk appears, showing a phase (gibbous, approximately 60–70 %). This is one of the rare cases where a planet displays a visible phase through a telescope.
Use an app (Stellarium, SkySafari, Star Walk) to locate Mercury before looking for it with the naked eye. Point toward the east-southeast, and the app will tell you exactly where to look.
Mercury looks like a comet. This was revealed by Dr. Sebastian Voltmer, a German astrophotographer based in Spicheren, France, in a series of photos that went viral on social media and was selected as NASA’s Image of the Day (APOD, May 3, 2022).
The solar wind and micrometeorites strip sodium atoms from Mercury’s surface. This sodium, illuminated by the Sun, forms a yellow-orange tail of sodium gas about 2.5 million kilometers long. It’s like a comet’s tail, but emanating from a planet. The phenomenon was predicted in the 1980s and observed for the first time two decades later.
Voltmer captured this tail from the Roque de los Muchachos Observatory on La Palma, using a 135-mm lens and a 589-nm filter tuned to the sodium emission line. Without this filter, the tail is invisible to the naked eye. With it, the tail appears in its full length. Voltmer also photographed Mercury’s surface (craters) using planetary imaging with a C11 EdgeHD telescope and documented the rapid evolution of the sodium tail over the course of a week.
His Ph.D. in scientific photography (University of Applied Arts Vienna) and his work at the intersection of media theory and astronomy have enabled him to take this type of photography to a level rarely achieved. His images are protected by copyright: we do not reproduce them here, but you can view them on his website (voltmer.photo) and his X account (@SeVoSpace).
For those who’d like to give it a try: you’ll need a 589-nm filter (sodium filter), a 135-mm lens or a telescope, a sensitive CCD or CMOS camera, and a very dark sky. The tail is most visible when Mercury is near the Pleiades, which isn’t the case in November 2026. However, the elongation on November 20 remains the best time to observe the planet itself.
The elongation on October 12, 2026 (already covered on the blog) was an evening elongation: Mercury was visible after sunset, low in the west. In the fall, the ecliptic forms a shallow angle with the western horizon in the Northern Hemisphere. Mercury remained very low (8–10°).
The western elongation on November 20 is a morning elongation. In the fall, the ecliptic is more open toward the eastern horizon. Mercury rises higher before dawn: 10–15° in altitude, sometimes higher depending on the latitude. This makes for more comfortable observing, even if it means getting up early.
A planetarium app (Stellarium, SkySafari) is essential for locating Mercury before sunrise.
We're not just a retailer. We test, advise, and provide support.
Discover our telescopes for observation and our frames for planetary observation.
This article is based on the ephemeris data from EarthSky (Mercury’s greatest western elongation, November 2026), In-The-Sky.org (Mercury elongation, November 20, 2026), and on Dr. Sebastian Voltmer’s work on Mercury’s sodium tail (APOD, May 3, 2022; voltmer.photo; @SeVoSpace). The image of Mercury is from the MESSENGER spacecraft (NASA / JHU APL / Carnegie Institution of Washington), in the public domain, via Wikimedia Commons.
CBurkhalter
Get comprehensive, free training by signing up for the newsletter.
