1. Photographs and a brief explanation of different types of galaxies



A composite image of the Messier 81 (M81) galaxy shows what astronomers call a "grand design" spiral galaxy,

where each of its arms curls all the way down into its center. Located about 12 million light-years away, in the Ursa Major constellation, M81 is among the brightest of the galaxies visible by telescope from Earth.

Photograph courtesy NASA/JPL-Caltech/ESA/Harvard-Smithsonian CfA

2. Sidney Girls High School Astronomy Club (Sidney, Australia) and NGC 6872 with IC 4970


This is the APOD: Astronomy Picture of the Day website from April 3, 2011.

Following is the brief Expert Explanation of this Gemini Observatory Astronomical "Cosmic Color Portrait

from the 8 meter Gemini South Telescope located in Chile, South America.


Over 400,000 light years across NGC 6872 is an enormous spiral galaxy, at least 4 times the size of our own,

very large, Milky Way. About 200 million light-years distant, toward the southern constellation Pavo, the Peacock, the remarkable galaxy's stretched out shape

is due to its ongoing gravitational interaction, likely leading to an eventual merger, with the nearby smaller galaxy IC 4970.

IC 4970 is seen just below and right of the giant galaxy's core in this cosmic color portrait from the 8 meter Gemini South telescope

in Chile. The idea to image this titanic galaxy collision comes from a winning contest essay submitted last year to the Gemini Observatory

by the Sydney Girls High School Astronomy Club. http://www.sghs.nsw.edu.au/

In addition to inspirational aspects and aesthetics, club members argued that a color image would be more than just a pretty picture.

In their winning essay they noted that "If enough colour data is obtained in the image it may reveal easily accessible information about:

1. the different populations of stars

2. star formation

3. relative rate of star formation due to the interaction

4. and the extent of dust and gas present in these galaxies".

(Editor's note: For Australian schools, 2011 contest information is here.)



This is the website with more specific information about the Contest and the Students' winning essay...