— Isaac Asimov, from “In Joy Still Felt” (Doubleday & Company, 1980)
There was an excellent reason why the famed science author Isaac Asimov and his wife Janet were jubilant on that night at sea. For they’d just had their very first take a look at essentially the most distant object that may be glimpsed with the unaided eye: the Andromeda Galaxy.
And this week, with the brilliant moon having left our evening sky, you too could have a probability to see this most amazing of deep sky objects, which can be passing almost directly overhead between 7:30 and eight p.m. local time.
Related: Night sky, November 2023: What you possibly can see tonight [maps]
Where to look
BEST BINOCULARS
Try our guide on the very best binoculars of 2023 to enable you find the best optics for viewing the Andromeda Galaxy or the rest within the night sky.
To seek out the Andromeda Galaxy, first locate the Great Square of Pegasus — a landmark of the autumn sky. Then, focus binoculars on the brilliant star Alpheratz, which is on the upper left corner of the Square. Then move straight across to the east (left) and get the star Mirach (in Andromeda) in your field of view. From there, crawl as much as a reasonably vibrant star above Mirach and proceed to run up in the identical direction until you will find the “little cloud” described by Al-Sufi, greater than a millennium ago.
That can be your stopping place, for you should have found the Andromeda Galaxy.
In the event you aren’t conversant in these stars or the Pegasus constellation, you might all the time use a stargazing app to enable you find the Andromeda Galaxy — but put the phone away as soon as you’ve got positioned it to let your eyes adjust to the dark night sky to make sure they will soak up as much light from this distant city of stars as possible.
Recall that the Asimov’s had the advantage of being positioned on shipboard in the course of the Atlantic after they made their Andromeda Galaxy sighting; not much concern about light pollution on the market! But to ensure that you to see it requires good eyesight and a dark, crystal-clear night with no street or house lighting nearby.
With the unaided eye it appears as nothing greater than an indefinite, mysterious glow; a diffuse elongated cloud perhaps two or thrice the apparent width of the moon.
The “Little Cloud”
The Andromeda Galaxy was supposedly first noted by the Persian astronomer Abd-al-Rahman Al-Sufi, who described it as a “little cloud” in his “Book of Fixed Stars” in 964 A.D. Nevertheless it can also have been known to Persian astronomers in what’s now Iran way back to 905 A.D., and even earlier. An authority on star nomenclature, Richard Hinckley Allen, once reported that it also appeared on a Dutch star map from the yr 1500.
Galileo’s rival, Simon Marius is often credited with the primary telescopic remark of this object in December of 1612. He described the nebula as an indefinite glow “like a candle shining through the horn window of a lanthorn (lantern).”
An incredible city of stars
Even today, binoculars and telescopes reveal this “cloud” as little greater than a smooth oval blur, which step by step brightens in the middle to a star-like nucleus. While it’s going to definitely look larger and brighter than along with your eyes alone, there’s little to suggest the grandeur of this object because it is usually shown in long exposure observatory photographs. It’s oval because from our vantage point we’re viewing it not removed from edgewise, but in truth, it’s an almost circular, flat spiral assemblage of star clouds.
The sunshine from that “little cloud” is definitely the full accumulation of sunshine from roughly one trillion (1,000,000,000,000) stars. It’s listed as Messier (“M”) 31, in Charles Messier’s famous catalog: hazy objects resembling comets, but later proved to be galaxies, nebulae and star clusters.
Here is essentially the most distant object that may be seen with the unaided eye. M31 has been estimated to be nearly 200,000 light years in diameter or one and a half times as wide as our own Milky Way galaxy. Its vibrant nucleus is the hazy patch that’s visible to the unaided eye.
Like our own galaxy, M31 has several attendant satellite galaxies. Two of those: M32 and M110 may be picked out with low magnification in a small-to-medium sized telescope, in the identical field of view as M31. There are yet two other smaller companions (NGC 147 and 185) that are much fainter and placed much farther away, near the border of nearby Cassiopeia.
Starlight that traveled a good distance
As you take a look at the Andromeda Galaxy tonight, you will be doing something that nobody else on the earth except a stargazer can do; you’ll actually be looking back into the distant past.
There may be a excellent reason that this patch of sunshine appears so very faint to the naked eye. While you see it tonight, consider that this light has been traveling some 2,500,000 years to succeed in you, traveling all that point on the tremendous velocity of 671 million miles (1.08 billion km) per hour. The sunshine you might be seeing is around 25,000 centuries old and started its journey across the time of the dawn of human consciousness. The sunshine you at the moment are getting is a minimum of 480 times older than the Pyramids; the space it has traveled is so inconceivable that even to jot down the variety of miles seems all but meaningless.
When it began its nearly 15-quintillion (15,000,000,000,000,000,000)-mile journey earthward, mastodons and saber-toothed tigers roamed over much of pre-ice-age North America and prehistoric man was struggling for existence in what’s now the Olduvai Gorge of East Africa.
And this is definitely only a neighbor of ours. With large observatory telescopes, we now have observed galaxies which might be over a billion light years away, or greater than 400 times farther than Andromeda!
Then consider those galaxies that the James Webb Space Telescope is currently detecting. Light left a few of them well over 13 billion years ago, inside just a couple of hundred million years of the Big Bang.
Cosmic collisions of the past … and future
Recent studies indicate that about six billion years ago, the Andromeda Galaxy was breached by one other large spiral galaxy. After several billion years, this intruder looped around Andromeda and at last smashed into its core and caused it to expand. Andromeda’s satellite galaxy, M32 — a small, compact elliptical galaxy — is regarded as the core of the renegade galaxy that collided with Andromeda. Initially it was itself probably a spiral galaxy, whose arms were stripped off by Andromeda’s gravity.
Interestingly, Andromeda is approaching our own Milky Way galaxy at a rate of 186.411 miles per second (300 km/s) and a galactic collision between the 2 is now anticipated to occur in about 4.5 billion years. Based on current calculations there’s a 50% probability that in such a merged galaxy, our solar system can be swept out thrice farther from the galactic core than its current distance. There may be also a 12% probability that the solar system can be ejected from the newly merged galaxy sometime in the course of the collision.
That is all a moot point thus far as life on Earth is anxious. In about 0.5 to 1.5 billion years the sun’s luminosity could have risen by 35% to 40%, likely initiating a runaway greenhouse effect on our planet. As a consequence, the surface of the Earth could have already develop into far too hot for liquid water to exist, ending all terrestrial life by the point the 2 galaxies collide.