Warm Up May 14, 2013 Have someone at your table carefully poke about 50 holes close together in the piece of paper with the pushpin Pin the paper to the blue wall in the front of the room. What does it look like? Can you see any individual pinholes? Does it look hazy? How is this like the Milky Way?

Agenda Warm Up Correct HW 15.4 Notes Bill Nye “Outer Space” Cool Down

15.4 Star Systems &Galaxies Our sun is a loner, but most stars are parts of star systems of 2 or more stars.

Binary and Triple Stars Groups of 2 or three stars locked together by gravity. These are NOT moons. Moons don’t carry out nuclear fusion.

Detecting Star Systems Often, one star in a system is brighter than the others, so how do we know it’s a system and not just one star? Wobble- Imagine a dancer with an invisible partner. You could tell from their movements that a partner must be present Eclipses- If a dim star passes between a brighter partner star and earth, we will see an eclipse.

Star Clusters A cluster is a group of stars that all formed from the same nebula Open Clusters – contain up to a few thousand randomly placed stars Globular Clusters – are large groups of up to a million densely packed stars Pleiades or Seven Sisters

Galaxies Lone stars and star systems are grouped in to larger collections of stars called galaxies. Galaxies are held together by gravity. Many galaxies, like our Milky Way, have a black hole at the center.

The Milky Way Galaxy Our home!

Other Galaxy Shapes Spiral – has “arms” Eliptical – no “arms” and tend to have older stars Irregular – not spiral or eliptical

Clusters of Galaxies Galaxies tend to appear in clusters as well. The Milky way is part of a galaxy cluster called the Local Group. The Local Group is then part of a larger system, the Virgo Supercluster

The Scale of the Universe Universe – all of space and everything in it It is hard to even imagine how big that is!

Scientific Notation Short way of writing numbers with LOTS of zeros 1. Write as number between 1 and Use exponent to represent number of decimal places Eames Video

Cool Down Title: Universe Brace Map 15.4 Vocab Booklet (11 words) Homework