Looking Up column: Barnard’s Star: Moving like a firefly

Peter Becker
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An artist's impression of Barnard's Star and its planet, which is about 3.2 times the size of Earth. [Photo by ESO/M. Kornmesser (Own work) [CC BY-SA 4 (], via Wikimedia Commons]

Where we live, June evenings bring fireflies - “lightning bugs” dancing their way across the starry background.

This is a real pleasure of stepping out on a clear night in June. The field we have out back, darkened by the night, would look like a field of stars if those fireflies would stand still. Instead they move about, blinking on and off, a show in my mind coupled with the constellations above, beats any man-made fireworks show.

One night I was looking through my reflecting telescope and a firefly entered through the open end of the tube. You can imagine the distraction!

The stars, though seemingly unchanging and still, looking as they did to our ancestors of old, aren’t all that different than the firefly. Like this flashy insect, the stars actually are in constant motion, and many of them “blink” - mostly at very slow rates (days, weeks, months) as they vary in magnitude.

The stars don’t seem to be shifting because they are so immensely far. A few though, are crossing the heavenly sphere at a fast enough clip and are close enough, that a user of even a small telescope could trace its motion over a few years. One of the most famous is Barnard’s Star, in Ophiucus.

As darkness falls in mid-June - once the moon is out of the way - look southeast for the large constellations Ophiucus and Serpens. Note: Serpens is broken in two, on either side of Ophiucus.

Ancient Greeks depicted Ophiucus as the renowned physican Aesculapius, the inventor and god of medicine, holding Serpens the Snake across his knees. Ophiucus is also depicted standing on Scorpius the Scorpion, the constellation immediately below it and marked with a fabulous, bright red star, Antares.

Dr. Ophiucus, I don’t think, would be recognized by my health insurance plan.

Barnard’s Star is of 9.5 magnitude, requiring a telescope of about 3-inch aperture or larger to easily see. You need a detailed star chart showing the myriad of similarly faint stars to track down which one is Barnard’s Star.

Although appearing motionless in the eyepiece, if you were to take photographs or very carefully plot the stars on paper, you could repeat this in a few years and see that Barnard’s Star has actually moved.

It was discovered by Professor Emerson Bernard in 1916. He noticed it had shifted by comparing his photographic plate with plates taken in 1894 and 1904.

The star has the highest proper motion of any star we see, moving at 10.3 “seconds of arc” per year.

(A degree on the sky, equal to about two full moons, is equivalent to 60 minutes of arc. Each minute has 60 seconds of arc.)

Barnard observed that in 22 years the star moved by four minutes of arc - about a third of the apparent separation of the famous double star Mizar and Alcor in the Big Dipper’s handle.

Barnard’s Star is a red dwarf star and only six light-years away, among the very closest. Astronomer Peter Van de Kamp, in 1963, had become convinced that an apparent wobble in the star’s path was due to the gravitational pull of an unseen planet.

His assertion was not vindicated until 2018 when a planet, 3.2 times the size of Earth, was discovered orbiting the star.

Full moon is on June 6.

Keep looking up at the sky!

Peter Becker is managing editor at The News Eagle in Hawley, Pennsylvania. Notes are welcome at Please mention in what newspaper or website you read this column.