Gemini Constellation

When you get started with your astronomy career, one of the first constellations that we learn about is Gemini. It is easily identified, and it closely resembles what it’s meant to – two twin brothers in the night sky.

For those interested in astrology, this constellation of course is part of the Zodiac family too. So, let’s look at some facts about the constellation Gemini.

  • Bordered By; Lynx, Monoceros, Auriga, Taurus, Orion, Canis Minor, Cancer.
  • Named after; The Twins
  • Declination; 20°
  • Brightest Star; Pollux
  • Best seen; Northern Hemisphere, December-January
  • Size rank; 30th
  • Constellation family; Zodiac
  • Pronunciation; JEM-IN-EYE

What is Gemini named after?

Gemini takes it’s named from the twins who were together known as Dioscuri, and individually known as Castor and Pollux. They are quite mysterious in mythology, as they are often referenced differently in different writings. Some writings have these twins as the sons of Zeus, and others have them as mortal men. They are known for their bravery and horse-riding ability, and they are referred to in many ancient writings like Homer’s Odyssey.

Who Founded the Gemini Constellation?

The origins of Gemini date back thousands of years, earlier than the Greek’s and at least as far back as the Babylonians. In more recent years, we often credit astronomer Philippe Loys de Chéseaux as one of the discoverers of this constellation.

How can I see the Gemini constellation?

The best way to find Gemini is by looking in the night sky for it’s brightest stars, which are called Pollux and Castor (after the Twins!). It borders constellations Taurus and Orion, which are also two of the easiest constellations for you to locate.

Main Stars of Gemini

There are many different stars within the Gemini constellation to look at. Let’s look at them in closer detail, and you can match them with the stars in the image below.

  • Pollux (β) – Pollux, also referred to as Beta Geminorum, is the brightest star in the Gemini constellation. It is also actually the closest giant star to our solar system’s star, the Sun. It makes up one of the faces of the two twins that Gemini resembles. It is approximately twice as massive as our Sun, and it actually has a smaller planet orbiting it too, which we refer to as Pollux b.
  • Castor (α) – Castor is the second brightest star in the constellation, and it makes up the face of the second twin. It’s also referred to as alpha geminorum. It is bright to us, and looks like it may just be made up of one giant star. However, it is actually made up of six stars, or three pairs of stars (a sextuple star system). It was first recorded in 1718, and is approximately 51 light years away from our planet Earth.
  • Alhena  (γ) – Alhena, also referred to as Gamma Geminorum, is a binary star system and the third brightest star in this constellation. It is approximately 109 light years away from the Sun, and it has more than 123x it’s luminosity.
  • Mebsuta (ε) – Epsilon Geminorum, or Mebsuta, makes up part of the body of the twin Castor. It’s mass is more than 19x that of the Sun, and it qualifies as a yellow G-type star.
  • Propus (η) – Prous makes up the foot of the twin Castor, and it is actually a triple star system. It is estimated to be 380 light years away from the Sun.
  • Wasat (δ) – Delta Geminorum, also called Wasat, makes up part of the twin Pollux. It is a triple star system within close proximity of the dwarf planet, Pluto.
  • Mekbuda (ζ) – Mekbuda, also referred to as Zeta Geminorum, makes up the abdomen of the twin Pollux. It is around 1200 light years from the Sun, and is thought to be a binary star.


In conclusion, Gemini is one constellation that everyone should know about. It’s very easy to find if you’re in the Northern hemisphere, and if you have kids that are interested in astronomy, then it’s a good idea to start with Gemini.