constellations & galaxies “the milky way has gone a little sour” - sam roberts

Constellations & Galaxies

“The Milky Way has gone a little sour”

- Sam Roberts

Constellations

• Groups of stars that form shapes or patterns – must be officially recognized– if not, the pattern is called an asterism

• named after ancient heroes/gods, animals or everyday objects

Test Your Knowledge

• Q: Is the “Big Dipper” an asterism or constellation

• A: Asterism

• The big dipper belongs to the constellation Ursa Major (The Big Bear)

Ursa Major (The Big Bear)

Ursa Minor (The Little Bear)

Polaris

Polaris

Polaris• Find Polaris in the night sky and you can

always find North

• It is commonly known as “The North Star”

• This is merely a geographical coincidence

• there is no “South Star”– Sigma Octantis is in the right location but it is so

faint to the naked eye that it is useless

Arcturus & Spica• Arcturus

– 4th brightest star– Brightest star in the

constellation Bootes

• Spica– 15th brightest star– Brightest star in the

constellation Virgo

• To find them, locate the Big Dipper and remember “Arc to Arcturus, then speed on to Spica”

Orion

Cassiopeia

Hercules

Zodiac Constellations

• Form a ring that the Sun seems to pass through each year as the Earth orbits around it.

• perhaps the most famous of all constellations because of their use in astrology

• There are 13 in total – Aries Leo Pisces– Taurus Virgo Sagittarius– Gemini Libra Capricornus– Cancer Scorpius Aquarius Ophiuchus

Cancer (The Crab)

Sagittarius (The Archer)

Gemini (The Twins)

Galaxies

• A galaxy is a large collection of gas, dust and hundreds of billions of stars

• Earth and the other planets are a part of the Milky Way Galaxy– Appears as a hazy white band in the night sky

• Andromeda is the nearest major galaxy

The Milky Way Andromeda

Types of Galaxies

1. Spiral – have a spiral shape- arms of spiral are mainly gas, dust and bright, young, blue stars

2. Elliptical – shaped like a football- composed of old stars

3. Irregular – no familiar shape

NGC 1232 M81

M51

Spiral Galaxies

NGC 5253

Elliptical Galaxies

M87

Irregular Galaxies

NGC 1705

Star Clusters• Groups of stars that are close together and travel

together are known as star clusters

• Star clusters are part of galaxies

• Open clusters – contain about 50 to 1000 stars – dispersed along the Milky Way’s main band

• Globular clusters– Contain 100 000 to 1 million stars arranged in spherical

shapes– Do not lie along the band of the Milky Way

Open Star Clusters

RCW 108

The Pleiades

The Pleiades

• also known as M45 or the Seven Sisters

• located in the constellation of Taurus

• dominated by hot, blue stars, which have formed within the last 100 million years.

• Of all clusters close to the Earth it is the best known and most striking to the naked eye

Harry Potter and the Observable Universe

http://astronomyspace.suite101.com/article.cfm/astronomical_names_in_harry_potter