According to astrologers, the Sun will set in Gemini on May 21. However, in reality, it will enter this constellation almost a month later, on June 20. Read the article to find out why this happens and what interesting things you can see in this constellation.
The Sun in Gemini
Astrologers say that on May 21, the Sun entered the sign of Gemini. However, this does not mean that it is now in the constellation of the same name. The reason for this lies in the fact that people who predict the future by the stars use observation data that was relevant 2000 years ago.
Since then, the point of the vernal equinox has shifted from Aries to Pisces, and, accordingly, the time of our luminary’s entry into other constellations has changed. In addition, their boundaries were clarified, which further confused the situation. You can read more about this in the article.
In the case of Gemini, the difference between the data of astrologers and astronomers turned out to be very large. After all, the latter know for sure that the Sun will enter the constellation Gemini only on June 20, the day before it leaves it, according to astrologers.
Because of this large difference between astronomical and astrological data, the constellation Gemini can be seen in the sky now, in the second half of May, albeit in a very limited way. This is not usually the case, because if the Sun is in a constellation, it is in the sky during the day.
As for the Gemini, their brightest stars, Castor and Pollux, can still be seen in the evening sky above the western horizon. You do not have to look for them in particular; you just need to look in the direction where the Sun has set, and two bright lights nearby will be what you are looking for.
The best time to observe the Gemini is in late fall and winter. Then they will rise high in the sky in the middle of the night, and you will be able to see not only the brightest stars, but also much dimmer objects. You can start looking for it in the Orion’s Belt. Then find the bright red star Betelgeuse in the same constellation and draw a line to it from the middle of the Belt. It will point to Gemini.
Confusion with Gemini
The name “Gemini” for this constellation was established in Babylonian texts. Back then, the pair of figures in the sky were seen as Lugalirra and Meshlamtaea, a pair of gods guarding the entrance to the underworld of the dead. They were either subordinates or embodiments of another god, Nergal, who was associated with the Sun, which burns all vegetation, and was generally the main god in the local hell.
However, now we know more about the ancient version of the Gemini myth, where the constellation is associated with a completely different twin, Castor and Pollux, or Polydeuces. They were born to the Spartan queen Leda as a result of one of Zeus’ many erotic adventures. It so happened that although they were twins, Pollux’s father was the supreme Olympic god himself, and Castor’s father was Leda’s lawful husband, King Tyndareus.
Together, Castor and Pollux took part in most of the heroic adventures described in ancient Greek myths, but it all ended badly – in one of the battles, Castor was killed and had to go to Hades, the ruler of the realm of the dead, as a mortal.
Pollux, as a god, was supposed to live forever in heaven. However, he did not want such a fate without his brother and persuaded Zeus to take him to heaven as well. Thus, they became a constellation, and the two brightest stars in it are named after them.
Gemini stars
Most often, the Alpha of any constellation is its brightest star. But this is not the case in Gemini. Here, the brightest star is Pollux, and it is the Beta of Gemini. It is 34 light years away, so it is the closest giant star to us.
Pollux is only 1.19 billion years old, but because its mass is 91% greater than that of the Sun, its evolution has already gone much further than in the case of our luminary. This star has already left the Main sequence, and its shells have begun to swell. Now the star’s diameter is almost 9 times larger than the Sun’s.
Since the early 1990s, the existence of a planet has been suspected at Pollux. In 2006, it was even confirmed that it was a gas giant 2.3 times more massive than Jupiter. It makes one revolution in 590 days. However, experts still doubt the reality of this planet.
The second brightest star in the constellation is Castor, which is less bright than its twin, but is considered the Alpha of Gemini. In the sky, these two luminaries are very close to each other, but in fact, the distance between them is about 16 light-years.
Castor is 49 light-years away from the Sun. It is not a single star, but a system consisting of six components. The main one is a white main-sequence star with a mass of 2.37 and a radius of 2.09 solar radii. A red dwarf with a mass of only 38% of the solar mass orbits it with a period of 2.21 days.
This pair, with a period of 459 years, orbits a common center of mass with another pair, which also consists of a white star and a red dwarf. In this second pair, the masses of the components are 1.79 and 0.39 solar masses, and they orbit each other in 2.93 days.
In turn, another pair of stars orbits the four aforementioned stars in a highly elongated orbit with a period of 14 thousand years. These are two red dwarfs with masses of about 0.6 solar masses each. They orbit each other in just 0.81 days. But that is not all. In 2018, it was suggested that a brown dwarf with a mass 49 times greater than that of Jupiter orbits the latter pair with a period of about 50 Earth years.
The third brightest star of the Gemini is their Gamma, called Alhena. It is a white star 2.8 times more massive than the Sun, 109 light years away from us. The fourth, μ Gemini, is also known as Tejat Posterior. It is a red giant that is 2.1 times more massive than the Sun and 80 times more luminous, 232 light-years away. Together, these two luminaries form the “legs” of the Gemini.
Variables in Gemini
Two variable stars located in this constellation are also interesting. The first of them is ζ Geminorum, or Mekbuda. It is also a multiple-star system, 1200 AU away from us, and consists of at least four components. Only the main one, which is a classical Cepheid, is well studied.
These stars are known for pulsating, sometimes shrinking in size, and sometimes expanding. The period of these processes depends on their luminosity. Specifically, Mekbuda has a mass of 7.7 solar masses and 10.2 days. During this time, it changes its apparent magnitude from +3.7 to +4.2.
The second interesting variable is the Gemini U. This is the so-called dwarf nova. The system consists of a white dwarf with a mass of 1.2 solar masses and a red dwarf with a mass of 42% of the solar mass, which orbit a common center of mass with a period of only 4 hours. Matter flows from the latter to the former.
The gas forms a shell around the dead star. At irregular intervals from 62 to 257 days, it flares up. As a result, the star’s brightness increases hundreds of times.
Other interesting objects
In addition, several noteworthy objects in the constellation Gemini are not single stars. The first of these is M35, a diffuse star cluster with 418 known members. It is located at a distance of 2800 light-years from us.
Another interesting object is the planetary nebula NGC 2392. It has several names: the Eskimo Nebula, the Clown Face Nebula, the Lion Nebula, and it really resembles a face surrounded by fur or a lace jabot. It is the remnant of a sun-like star that has passed the red giant stage and shed its shells.
Another interesting object, though no longer accessible to amateur telescopes, is Geminga. It is one of the neutron stars closest to Earth. Its distance is about 800 light years. Interestingly, its nature remained completely unclear for some time. It was discovered as an extremely bright X-ray source back in 1975. However, in other ranges, including optical, it could not be identified with any object for a long time. It was only in 1992 that it was discovered in the X-ray, and in 1996 in the radio range that it became finally clear what it was.
