APOD 4.5 Carina Nebula Panorama from Hubble

Spanning 300 light years across and 7,500 light years away in the constellation Carina is this amazing nebula, NGC 3372, also known as the Great Nebula in Carina. Eta Carinae is the most active star in this nebula and was once the brightest in the 1830's before suddenly fading. In the Keyhole nebula, left of center, some of the most massive stars known are located there.

This false color image was taken by the Hubble Telescope and is the most detailed picture taken of this nebula. It is a composite of 48 high-resolute frames and was released in honor of Hubble's 17th anniversary. Wide-field annotated and zoomable image versions are available.

APOD 4.4 NGC 5139: Omega Centauri

This picture is quite stellar, literally. Shown here is the largest known globular cluster in our galaxy. Omega Centauri is in the constellation Centaurus, a constellation that holds many wonders including the closest star system-Alpha Centauri. Omega Centauri is a wonder in itself. Most globular clusters are made out of old stars but Omega consists of a range of ages. In fact with it consisting of over 10 million stars and 150 light-years across, it may be the remnant of the core of a smaller galaxy that has merged with our own Milky Way.

APOD 4.3 Americans Defeat Russians in First Space Quidditch Match

Now this is an interesting Picture. After playing a hard fought match against the Russians, American astronaut Michael Lopez-Alegria has caught the elusive snitch. Making the final score... Just Kidding! This picture was posted on April Fools Day, and although a quidditch match would have been interesting (had it been possible), the picture shows American astronauts space walking to help build the International Space Station.

Galaxies: Normal and Active

Normal:
Main Types-Spirals- Sa, Sb, Sc Sa-tightest arms Sc-loosest arms http://www.creationofuniverse.com/1024/images/Spiral_Galaxy_jpg.jpg
Barred-Spirals- SBa, SBb, SBc http://www.coe.berkeley.edu/forefront/spring2006/images/seti3.jpg
Elliptical-E0-E7, E0-least elliptical E7-most Elliptical
http://www.nasm.si.edu/exploretheuniverse/kiosks/whatsnew/whatsNewImages/April24pressreleasephotos.jpg
Irregular http://cache.eb.com/eb/image?id=21267&rendTypeId=4


Sizes: Spirals/Barred- 5-100kpc diameter, 10^9-10^12 solar masses
Ellipticals- 1/10 -100kpc diameter, 10^7 up to 10^13 solar masses
Irregulars- 1-10kpc diameter, 10^8-10^10 solar masses


Characteristics- Spirals-Thin and flat spiral structure with a central bulge, disk and arms, has lots of dust and clouds and has star formation mostly in arms.
http://nrumiano.free.fr/Images_gx/structure_gx_E.jpg
http://csep10.phys.utk.edu/astr162/lect/galaxies/spiral.html
Barred-Spirals- Same as spiral but core has a band of stars, gas, and dust. Arms extend from this bar.
Ellipticals-Has no arms or spiral structure, no disk, little dust and gas, little to none star formation, tend to have older stars.
Irregular-Has little symmetry in there structure, has active star formations, every other type of galaxy, but Active Galaxies

Active Galaxies: Galaxies with active violent processes in the center. May have jets, X-ray bursts, other radiation, and or unusual structures esp. of the nucleus
http://glast.sonoma.edu/images/AGN.jpg

Origins of Galaxies: Don't know specifics, Article:
http://www.space.com/scienceastronomy/astronomy/cosmic_galaxies_020122-1.html