Hubble Deep Field Galaxy Estimate
This is one of my favorite exercises in the Astronomy course.
One large area of the science standards is knowing our place in space and getting
a proper perspective. Well, the Solar System Scale Model gives you a sense of
where Earth is relative to the other planets and the nearest stars. This lab
will give you a perspective Earth's larger home as a member of the Milky Way
relative to other galaxies in the Universe.
The image above is the Hubble
Ultra Deep Field. It is the deepest look ever into the most distant areas
of the Universe. The Hubble Telescope's Advanced Camera for Surveys' wide-field
camera snapped 800 exposures over four months, from Sept. 24, 2003 to Jan. 16,
2004. Each exposure averaged 21 minutes in length, bringing the total exposure
time to 1 million seconds! The total image is described as "looking through
an 8 foot-long straw" at a tiny patch of the night sky and seeing what
is in that limited amount of sky. Click on the link in this paragraph to learn
more. When the imaging process was completed, this photo is what greeted astronomers!
In the image at the top of this page, objects that have four little points are
foreground stars in the Milky Way. Every other dot is a galaxy! In this lab
will you study this image and estimate the total number of galaxies in the Universe.
The first thing you are asked to do is make a guess as to the
number of galaxies you think are in the entire Universe. Once you have made
this guess, write that number down someplace for later reference. Now, the next
step is to enter the practice area for the galaxy estimate. Please go to the
Ultra Deep Field Lab page. When you arrive
there, do the galaxy counts as you are instructed. When you have collected those
counts, you will be asked to return to this page and enter the values into the
boxes found below. A WARNING. THE IMAGE ON THE PAGE YOU WILL CONNECT TO IS
A 3.5MB IMAGE. IT IS HUGE! I hope your computer can manage an image of this
size because there is no other way to really count the galaxies unless I give
you the full resolution image ... and I even cut it down a bit from the original
6000x6000 format into a 4000x4000 format or else my webpage builder would not
let me move it into the course.
You need to fill in the two blanks below
correctly or else nothing that you work on will arrive to me via the internet.
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