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