Welcome to another edition of Constellation Friday! Today, in honor of the terrific and late Tammy Plotner, we have a look at “the Twins”– the Gemini constellation. Delight in!
In the 2nd century CE, Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy) put together a list of the then-known 48 constellations, the sum total of thousands of years worth of stargazing and charting the paradises. This writing, known as the Almagest, would be utilized by medieval European and Islamic scholars for over a thousand years to come, efficiently making it the astrological and astronomical canon till the early Modern Age.
One of the original 48 is Gemini, a constellation situated on the ecliptic airplane between Taurus (to the west) and Cancer (to the east). Its brightest stars are Castor and Pollux, which are simple to identify and represent the “Twins,” which is where it got its label. Gemini is bordered by the constellations of Lynx, Auriga, Taurus, Orion, Monoceros, Canis Minor, and Cancer, and has since entered into the 88 modern-day constellations recognized by the International Astronomical Union.
Name and Meaning:
In mythology, Gemini is associated with the Greek myth of Castor and Polydeuces. The 2 bros Castor and Pollux were identical twins, so no one could inform them apart.
An amphora dating between 540-530 BCE that shows Castor and Pollux. Credit: Egisto Sani/Flickr
The bros were known to be in shape and all set, so Pollux was the very first Argonaut to take on the obstacle. As soon as he got a clear shot, Pollux drove his fist into Amycus temple, squashing his skull and ended the battle. Nevertheless, the tale ends rather regretfully. Their final adventure took them to lands of Arcadia with two cousins (ex-Argonauts) to raid cattle. When their ill-gotten booty was divided, the cousins ran and took the loot. Of course, Castor and Pollux followed, taking a faster way to wait.
Regrettably, a cousin found Castor first shot him. The other cousin knocked him unconscious with a rock and went in for the kill when Pollux avenged his bro. Thankfully, Zeus was seeing and ended the ordeal with a thunderbolt. When Pollux restored consciousness and recognized Castor was join, he asked Zeus to eliminate his immortality. Zeus gave his desire and positioned the twins in the sky to remind us of all of brotherly love.
History of Observation:
The Gemini constellation and “The Twins” have been acknowledged by cultures since ancient times. To the ancient Babylonians, the stars were understood as the Great Twins and were determined as the minor gods Meshlamtaea and Lugalirra– which translates to “The One who has actually emerged from the Underworld” and the “Mighty King” (respectively). Both of these names were titles held by Nergal, the god of pester, pestilence, and the king of the Underworld.
In Egyptian astrology, the constellation was determined with 2 goats, while Arabian astrology associated them with twin peacocks. To the Romans (who sent the Greek association with Castor and Pollux to Europe), these stars were frequently identified with the bros Romulus and Remus– the legendary founders of Rome. To Chinese astronomers, the stars that are part of Gemini are situated in two corners of the zodiac: the White Tiger of the West (X?
In 147 or 148 CE, Ptolemy included Gemini as one of the 48 constellations included within the Almagest. In 1930, the International Astronomical Union (IAU) consisted of Gemini and its existing boundaries in their main list of the 88 contemporary constellations.
A photo of Castor and Pollux showing their color differences. Credit: Rogelio Bernal Andreo/ RBA Premium Astrophotography
Significant Features:
There are two annual meteor showers connected with the constellation of Gemini. The very first peaks on or around the date of March 22nd, and are referred to as the March Geminids. This Geminid meteor shower was very first discovered in 1973 and after that verified in 1975. The typical fall rate is normally about 40 per hour, but the meteoroid stream is unstudied and it may vary. These appear to be extremely slow meteors, entering our environment unhurriedly and leaving enduring tracks.
The second meteor shower related to Gemini are the Geminids themselves, which peak on or near the date of December 14th, with activity starting approximately 2 weeks prior and last numerous days beyond the date. The Geminids are among the most hauntingly beautiful and strange displays of celestial fireworks all year– first noted in 1862 by Robert P. Greg in England, and B. V. Marsh and Prof. Alex C. Twining of the United States in independent research studies.
The yearly look of the Geminid stream was weak at first, producing no greater than a few per hour, however it has grown in strength during the last century and a half. By 1877, astronomers had realized this was a new yearly shower– producing about 14 meteors per hour. At the turn of the last century, the rate had actually increased to over 20; and by the 1930s, approximately 70 per hour. Just ten years ago observers tape-recorded an outstanding 110 per hour during a moonless night …
So why are the Geminids such a mystery? The majority of meteor showers are historic– recorded and taped for centuries– and we know them as originating with cometary particles. However when astronomers began searching for the Geminids moms and dad comet, they found none. It wasnt up until October 11th, 1983, that Simon Green and John K. Davies, utilizing information from NASAs Infrared Astronomical Satellite, spotted an item (validated the next night by Charles Kowal) that matched the orbit of the Geminid meteoroid stream.
This was no comet, it was an asteroid– in fact, a 14th magnitude asteroid which is passing Earth this evening from a distance of less than 18 million kilometers! Now thought about a Potential Hazardous Asteroid (PHA), 3200 Phaeton comes within 3.2 million kilometers of Earths orbit about every 17 months. Originally designated as 1983 TB, however later on relabelled 3200 Phaethon, this obviously rocky solar system member has a highly elliptical orbit that puts it within 0.15 AU of the Sun during every planetary system trip.
Picture of Messier 35, a Deep-Sky Object located in the constellation Gemini. Credit: 2MASS
The initial hypothesis was that considering that Phaethons orbit passes through the asteroid belt, it might have clashed with one or more asteroids, developing rocky debris. Now our asteroid is acting like a comet, yet it doesnt develop a tail.
What precisely is this “thing?” Well, we do know that 5.1 kilometer size Phaethon orbits like a comet, yet has the spectral signature of an asteroid. By studying pictures of the meteor showers, researchers have figured out that the meteors are denser than cometary material, yet not as dense as asteroid pieces. This leads them to believe Phaethon is probably an extinct comet which has gathered a thick layer of interplanetary dust during its travels, yet keeps the ice-like nucleus. Up until we are able to take physical samples of this “mystery,” we might never ever completely understand what Phaethon is, but we can completely appreciate the yearly display it produces!
The radiant for the shower is near the brilliant star Castor, however meteors can stem from many points in the sky. From around 2 AM tonight until dawn (when our local sky window is aimed directly into the stream) it is possible to see about one “shooting star” every 30 seconds.
The most successful of observing nights are ones where you are comfy, so make certain to utilize a reclining chair or pad on the ground while looking up … And dress warmly! When possible– it will triple the quantity of meteors you see, please get away from light sources.
Finding Gemini:
Gemini is bordered by the constellations of Lynx, Auriga, Taurus, Orion, Monoceros, Canis Minor, and Cancer. It covers roughly 54 square degrees of sky and contains 17 main stars in the asterism, with 80 stars possessing Bayer/Flamsteed designations.
The place of the constellation Gemini in the night sky. Credit: AugPi/ Wikimedia Commons.
Lets start first with Alpha Geminorum– the “a” symbol on our map. This is Castor. It might look like just a single star in field glasses, its really rather an outstanding triple star system in a telescope. Here you will find 2 comparable magnitude stars separated by simply a couple of seconds of arc– and both of these stars are binary stars, too! The faint, far-off orange star, Castor C, is likewise a double star, consisting of nearly similar, low-mass M stars– red dwarfs– and either one, or both of these are flare stars. Pretty amazing, huh?
Pollux is the 17th brightest star in the sky, and this orange giant star is unusual, too. Pollux has a hot, external, magnetically supported corona maybe similar to that surrounding our Sun. If we were there, how big would orange huge Pollux appearance in the sky?
Our next target is Delta Geminorum– the “8” shape on our map. Delta goes by the standard name of Wasat, which implies middle. Luckily, thats right about where its located! Wasat is located very close to the ecliptic airplane, and it is an essential star given that it often gets occulted by the Moon. Thats not all. Wasat is also a fantastic double star, too. Get the telescope and have an appearance at this soft white star with the disparate orange companion. Its a delicious treat!
Now head even more down the line for Gamma Geminorum– the “Y” shape on our map. Its name is Almeisan and it has to do with 150 light-years away from Earth. A binary star? You bet. The significant star is a spectroscopic binary but make sure to try to find a faint optical buddy too. Hop throughout the constellation to Theta Geminorum, the “n” shape. Often called Nageba, this 200 light-year far-off Class A3 star is also a binary that can be split with a telescope. Look for components of magnitudes 3.60 and 5.18, separated by 2.9 arcseconds.
Last on our list of stars is Epsilon Geminorum, the backward “3”. Its name is Mebsuta and it has to do with 900 light-years away from our planetary system. Mebsuta is a supergiant star of spectral class G5 and, compared to our Sun, is 150 times larger. Like Delta on the other side of Gemini, Epsilon is also extremely near the ecliptic aircraft and can also be occulted by the Moon or worlds. Be sure to likewise watch on Zeta Geminorum, too! It is a cepheid variable star, with really nice magnitude modifications from 3.62 to 4.18 every 10.15 days. Quite worth following!
The areas of the Gemini constellation in the night sky. Credit: IAU/Sky & & Telescope Magazine
Before you put away your field glasses, travel back to Theta and make a hop over to the magnificent Messier 35. Listed as NGC 2168, the remarkable open star cluster was found by Philippe Loys de Chéseaux in 1745 and separately discovered by John Bevis prior to 1750. Progressively larger optics will expose more and more stars … several hundred stars in a location about the size of the moon. Maybe 100 million years old, this collection of excellent gems includes a number of yellow and orange huge stars to thrill the eye– but big telescopes will see something else.
Located about 15 arc minutes southwest of M35 is another stellar cluster– NGC 2158. NGC 2158 is over 10 times older and over 5 times more remote than M35!
For the telescope, theres no location like NGC 2392 (RA 7:29; Dec 20:55) about 4 degrees east/southeast of Wasat. Better referred to as the “Eskimo Nebula”, this planetary nebula has an intense main area and the surrounding dim ring structure. Make sure to up the zoom in even a small telescope on this one. This outstanding relic was very first spied by William Herschel in 1787 and is a bubble of product being blown into area by the central stars intense “wind” of high-speed product. Attempt including a nebula filter to highlight various and subtle information!
This open cluster is most likely a billion years old– nearly all of its members evolved to the red giant star phase. Look for a reasonably well-compressed area of looping faint stars with a combined magnitude of near 10.
This near 8th magnitude galactic star cluster is abundant in solar-type stars– another scientific play ground for discovering about the origins and advancement of the Milky Way. With almost 1000 stars loaded largely together in a small area, NGC 2420 initially belonged to another small galaxy that was cannibalized by our own. With an approximated age of 1.7 billion years old, it stays an interest due to the fact that it is moving quickly through area– and because it hasnt been tidally pulled apart by our galactic disc.
There are other star clusters to enjoy in the constellation of Gemini also, so get an excellent star chart and enjoy your time with the “Twins”!
We have actually written lots of fascinating posts about the constellation here at Universe Today., and Zodiac Signs And Their Dates.
Be sure to have a look at The Messier Catalog while youre at it!
To find out more, inspect out the IAUs list of Constellations, and the Students for the Exploration and Development of Space page on Canes Venatici and Constellation Families.
Sources:
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It covers approximately 54 square degrees of sky and includes 17 main stars in the asterism, with 80 stars possessing Bayer/Flamsteed classifications. It might look like simply a single star in binoculars, its really quite an impressive triple star system in a telescope. Here you will discover 2 similar magnitude stars separated by simply a couple of seconds of arc– and both of these stars are binary stars, too! The faint, distant orange star, Castor C, is likewise a double star, consisting of nearly identical, low-mass M stars– red dwarfs– and either one, or both of these are flare stars. Pollux is the 17th brightest star in the sky, and this orange giant star is uncommon, too.
