How To Quickly Find & See Mercury Through A Telescope
Mercury is often cited as the most difficult of the naked-eye planets to see. Because it’s the closest planet to the sun, it is usually obscured by the light from our star.
But, can you see Mercury through a telescope?
Mercury can be viewed through a telescope when it lies at one of its elongations, either farthest west of the Sun in the eastern morning sky or farthest east of the Sun in the evening sky. Exercise caution while looking for Mercury with a telescope as it’s always close to the sun.
So how do we know when and where to look to find Mercury? Read on, to find out more about our mysterious neighbor.
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How To Find Mercury In The Night Sky With A Telescope
Mercury has been known since very early times, but it is never very conspicuous, and there are many people who have never seen it at all.
The reason for this is that it always seems to keep close to the sun in the sky, and can never be observed against a dark background.”
Because Mercury never strays too far from the Sun, it is often lost in the Sun’s glare. Never, ever attempt to locate and observe Mercury in broad daylight as it is extremely dangerous and not worth the risk of accidentally blinding yourself and causing permanent eye damage.
Only during a favorable separation from the Sun is it relatively safe enough to observe Mercury in a deep twilight sky when the Sun is below the horizon.
Note: Attempting to observe Mercury during the day can be dangerous as Mercury is the closest planet to the sun in our solar system. Not only will Mercury be very difficult to observe during the day, but you may also risk serious and permanent damage to your eyes.
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When Can You See Mercury In 2021
Mercury can be safely observed during favorable periods when it reaches its greatest separation from the Sun. Astronomers refer to this as “greatest elongation.”
Because Mercury is so close to the Sun, elongations occur every few months, placing the planet on either the east or west side of the Sun.
Due to its tight orbit, Mercury can only go as far as 28 degrees from the sun even at its maximum elongation.
Evening: January 10 to January 31
On January 10, Mercury, Jupiter, and Saturn will come together and form a small triangle low in the southwestern sky. You may look for Mercury 30 to 45 minutes after sunset.
You may use a small telescope to look for it.
On January 24, Mercury will reach the greatest eastern elongation of 18.6 degrees from the Sun. This is the best time to view Mercury since it will be at its pinnacle above the horizon in the night sky.
Morning: from February 28 to March 20
On March 6, Mercury will reach the greatest western elongation of 27.3 degrees from the Sun.
You can clearly see Mercury at this time because it will be at its highest point above the horizon in the morning.
You may find Mercury with a starter telescope low in the eastern sky just before sunrise. On the morning of March 5 prior to sunrise, Mercury will appear just to the left of Jupiter.
Evening: from May 3 to May 24
On May 17, Mercury will reach the greatest eastern elongation of 22 degrees from the Sun. This is when Mercury will be at its highest point above the horizon in the evening. You may find Mercury low in the western sky just after sunset.
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Morning: from June 27 to July 16
Mercury stands at the greatest elongation west (22 degrees from the sun) on Independence Day morning, but this apparition is unfavorable for observers in mid-northern latitudes.
Look for it 45 minutes before sunrise just above the east-northeastern horizon.
It’s 11 degrees to the lower left of the star Aldebaran and 26 degrees to the lower right of Capella.
The planet’s magnitude is +0.5 and a telescope shows its small globe 35% illuminated. For the next two weeks, as this speedy planet brightens to magnitude -1, it can be seen much more easily as more of its lighted side is turned toward us.
But late in the month, it will quickly move into the glare of the sun, passing superior conjunction (on the sun’s far side) on Aug. 1. On the morning of July 8, an exceedingly narrow (3% illuminated) waning crescent moon will be positioned about 4.5 degrees to the left of Mercury.
Evening: from August 31 to September 21
On September 14, Mercury will reach the greatest eastern elongation of 26.8 degrees from the Sun.
This is when Mercury will be at its highest point above the horizon in the evening sky. You may find Mercury low in the western sky just after sunset.
Morning: from October 18 to November 1
On October 25, Mercury will reach the greatest western elongation of 18.4 degrees from the Sun.
This is the best time to view Mercury since it will be at its highest point above the horizon in the morning sky.
You may find Mercury low in the eastern sky just before sunrise.
Use Astronomy Apps & Star Charts
Once you know when Mercury will be visible in the evening/morning sky, you may take refer to star charts in astronomy-related magazines, books, or websites to help you find Mercury’s exact location.
Stargazing apps are brilliant for spotting Mercury in the night sky, looking at other planets, identifying stars, and learning about astrology. Whether you’re a beginner or a stargazing pro, these user-friendly apps are your ultimate guide to finding Mercury in the enormous sky.
You may use Star Walk 2, Sky View, Star Chart or, Google Sky to locate Mercury for you. Most of them have some kind of augmented-reality feature, where they can locate where you are automatically and pull up what the star map should look like above you.
Which Telescope Is Best To View Mercury
While it is rewarding to spot Mercury with your naked eyes, even a small beginner-friendly telescope can help you locate it as soon as the Sun dips safely below the horizon and the sky begins to fade into twilight.
A computerized telescope of at least 4” aperture, with tracking ability, would be a great choice to view Mercury as it will keep the planet centered for a good stabilized view.
Mercury will be low on the horizon, in a part of the atmosphere that is thicker and more susceptible to atmospheric turbulence. That means Mercury will look like a shimmering or twinkling star as it shines through the unstable air.
What Magnification Do You Need To See Mercury?
To see surface detail on the planet Mercury, a magnification of at least 200 to 250x is recommended. Following the generally accepted rules of maximum magnification which is 2 times the aperture in millimeters, at least a 100 mm telescope is recommended to resolve detail at this high power.
To counteract some of the detrimental effects of the atmosphere and reduce the glare of the bright disk, I highly recommend using an orange or red filter.
I use the #23A light red, you may also use #21 orange also. #25A red is useful with large apertures.