If there is one thing that has bothered me most in my more than 50 years of working in the field of astronomy, it is that most astronomy books give the impression that the planet Mercury is a very challenging, if not nearly impossible, object to see. In fact, this has earned the planet the nickname “hard-to-find planet.”
For example, a passage from “The ABC’s of Astronomy” by Roy A. Gallant (Doubleday & Company, Inc. 1962): “Mercury is the most difficult planet to observe, having little to offer and being too small and too close to the sun to be seen.” difficult.”
This certainly doesn’t sound very inviting to anyone who might want to try seeing Mercury with their own eyes. But still, viewing prospects are not as bleak as this passage suggests. In fact, in some cases, Mercury isn’t actually that elusive. You just need to know when and where to look and find a clear horizon. For example, it is important that Mercury be positioned as directly above the location of the Sun as possible; This is a condition best accomplished just after sunset in late winter or early spring and before sunrise in autumn or early winter.
Relating to: Night sky, March 2024: What you can see tonight
Mercury is called the “inferior planet” because its orbit is closer to the Sun than Earth’s. Therefore, from our perspective it always appears to be in the same general direction as the sun. So relatively few people saw it; There is even a rumor that Copernicus, who lived in northern Poland, never saw it. But it’s actually not hard to see this. You just need to know when and where to look and find a clear western horizon.
A three week window
TOP TELESCOPE SELECTION:
Need a telescope to get out there and see Mercury? We recommend the Celestron Astro Fi 102 as our top pick in our guide to the best telescopes for beginners.
And for those living in the Northern Hemisphere, we’re currently in the middle of a nice “window of opportunity” to view Mercury in the evening sky. This window, which will close after March 31, will continue to provide good chances for you to see this so-called “hard-to-find planet” with your own eyes.
Currently, Mercury is visible very near the western horizon about 45 minutes after sunset. But if the sky is clear and there are no tall obstacles (like trees or buildings) obstructing your view, you will have no problem seeing it as a very bright “star” that shines only with a yellowish-orange tint. Currently, Mercury shines at a very bright brightness of magnitude -1.3. In fact, among stars and planets, Mercury now ranks a very respectable fourth behind Venus, Jupiter and Sirius (the brightest star).
In the evenings that follow, Mercury’s brightness will gradually decrease at first, but it will also reach its greatest elongation at 19 degrees east of the Sun on March 24. (the similarly colored star Arcturus in Boötes), Mercury will appear 22 degrees below and to the right of Jupiter. The width of your clenched fist, extended at arm’s length, is roughly ten degrees. In other words, Mercury will be positioned just above the “two fists” to the lower right of Jupiter. Mercury will also set 90 minutes after the sun. It will even set in a dark sky after the end of evening twilight from March 20 to 28.
As a result, this will be the best evening view of Mercury in 2024.
Like Venus, Mercury appears to go through phases like the Moon. In early March, when Mercury began to appear very low in the western twilight sky, it was almost a full disk, so it now appears almost as bright as Sirius. It will appear 43 percent illuminated when it reaches maximum elongation, and the amount of its surface illuminated by the sun will continue to decrease in the coming days. So after March 24th, as it begins to rotate closer to the Sun, it will begin to fade quite quickly.
In fact, on the evening of March 31, Mercury’s brightness will have decreased to +1.4 magnitude; It is slightly dimmer than the star Regulus in Leo and only 1/12 as bright as it is now. It will be seen in telescopes as a contracting crescent phase. This will likely be the last time you see it, as its rapid fading and descent into the brighter sunset glow will eventually render Mercury invisible in early April.
More than a thousand degrees difference!
In ancient Roman legends, Mercury was the swift-footed messenger of the gods. The planet is so named because it is the closest planet to the sun and the fastest of the solar family, having an average speed of 30 miles per second; It makes its annual journey in just 88 Earth days.
Interestingly, the time it takes for Mercury to rotate once around its axis is 59 days, so periods of intense heat and extreme cold occur all over its surface. Although its average distance from the Sun is only 36 million miles (58 million km), Mercury experiences by far the widest temperature range: 790° F (420° C) on the dayside; -270° F. (-170° C) on the night side.
Dual ID
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In pre-Christian times, this planet actually had two names, because it was not realized that it could appear alternately on one side of the sun and then on the other. When Mercury was in the evening sky he was called Mercury, but when he appeared in the morning he was known as Apollo. In the 5th century BC, Pythagoras is said to have pointed out that they were actually one and the same.
If you’re hoping to catch a glimpse of Mercury, our guides to the best telescopes and best binoculars are a great place to start. If you’re looking to take photos of the night sky in general, check out our guide to the best cameras for astrophotography and the best lenses for astrophotography, as well as how to photograph planets.
Editor’s Note: If you capture an image of Mercury and would like to share it with Space.com readers, send your photos, comments, name and location to spacephotos@space.com.
Joe Rao is an instructor and visiting professor in New York Hayden Planetarium. writes about astronomy Natural History magazine, Farmer’s Almanac and other publications.