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First Published 5th January 2012, Last Updated by

Constellation guide to the 88 official constellations which divide up the sky. These constellations are used to help navigate the celestial sphere. The Constellations are patterns in the sky which have been to invented and have deep mythology behind them. Constellations cover massive areas in the sky and as such are very easy to find.
Astronomical Objects Series
  1. Guide to the Constellations and Mythology
  2. What are Asteroids, Meteors and Comets?
  3. Binary Stars and Double Stars
  4. Variable Stars
  5. Supernova and Supernovae
  6. Types of Nebula and Nebulae
  7. What Is a Black Hole? Black Holes Explained - From Birth to Death
  8. Quasars
  9. Pulsars - The Universe's Gift to Physics
  10. What is inside a Neutron Star?
  11. Gamma Ray Bursts
  12. Kuiper Belt
  13. What is an Exoplanet?
  14. Galaxy Types and Galaxy Formation
  15. The Messier Catalogue
  16. The Caldwell Catalogue
  17. 25 Stunning Sights Every Astronomer Should See

Constellations are usually one of the first things new astronomers start observing, and something many professionals totally ignore in there exploration of deep space. Constellations aren't real objects, they are a figment of our creative imaginations.

Over the millennia we have grouped stars together to form imaginary outlines or meaningful patterns on the celestial sphere, typically representing animals, mythological people or gods, mythological creatures, or manufactured devices. The entire sky is divided up into 88 areas, each one a constellation. They help us navigate the night's sky, and navigate the Earth.

A constellation is a group of stars that make an imaginary shape in the night sky.

A constellation is a group of stars that make an imaginary shape in the night sky.

Constellation names, like the names of stars, come from a variety of sources and each has a different story and meaning to it. Some of the constellations have very familiar names, such as Leo, Gemini, Virgo and Aquarius. These are some of the 12 constellations which form the Zodiac. The Zodiac constellations follow the line of the ecliptic. The ecliptic is the apparent path of the Sun on the celestial sphere.

Although not an official constellation, the Plough is the most famous and easily recognised.

Although not an official constellation, the Plough is the most famous and easily recognised.

Not all of the constellations are visible from any one point on Earth. The star maps are typically divided into maps for the northern hemisphere and maps for the southern hemisphere. The season of the year can also affect what constellations are visible from where you are located on Earth.

The Big Dipper, shown above, isn't official, but one of the many unofficial constellations called Asterisms. An asterism might form part of an official constellation, like the Big Dipper, which is composed of the seven brightest stars in the constellation Ursa Major. Or the constellation might be made up of stars from different constellations. For example, the three points of the Summer Triangle asterism are Deneb, Altair, and Vega, which are the brightest stars in the constellations Cygnus, Aquila, and Lyra, respectively.

You can view more about each of the individual constellations and their mythology in the links below.

Tutorial Series

This post is part of the series Astronomical Objects. Use the links below to advance to the next tutorial in the couse, or go back and see the previous in the tutorial series.

Boötes

The Herdsman

Location: Northern Spring - 15h RA 30° Dec

Boötes is generally referred to as the Bear Watcher, since it appears to be watching over the constellations Ursa Major and Ursa Minor.

The name Arcturus, the alpha star of Boötes, means bear driver. It is a zero magnitude red giant and is the third brightest star as seen from Earth in the night sky. It is one of the vertices's of the Spring Triangle, the other two being Spica (α Virginis) and Denebola (ß Leonis).

Boötes

Boötes Mythology

Exactly whom Boötes is supposed to represent is not clear. According to one version, he was a ploughman who drove the oxen in the constellation Ursa Major using his two dogs Chara and Asterion (from the constellation Canes Venatici). The oxen were tied to the polar axis and so the action of Boötes kept the heavens in constant rotation.

Boötes Deep Space Objects

Boötes has two bright galaxies. NGC 5248 (Caldwell 45) is a type Sc galaxy (a variety of spiral galaxy) of magnitude 10.2. NGC 5676 is another type Sc galaxy of magnitude 10.9. Boötes is home to the Quadrantid meteor shower, the most prolific annual meteor shower.

Constellations

Northern Circumpolar Constellations

These constellations can be viewed all year round in the Northern hemisphere as they move in a counterclockwise direction around the north celestial pole without setting or dipping below the horizon.

Northern Spring Constellations

These Northern constellations are best viewed around the spring months. The rest of the year the constellation will not rise during the night.

Northern Summer Constellations

These Northern constellations are best viewed around the summer months. The rest of the year the constellation will not rise during the night.

Northern Autumn Constellations

These Northern constellations are best viewed around the autumn months. The rest of the year the constellation will not rise during the night.

Northern Winter Constellations

These Northern constellations are best viewed around the winter months. The rest of the year the constellation will not rise during the night.