Explanation:
What was the very early universe like?
To help find out, astronomers pointed the
Hubble Space Telescope
between bright nearby objects to create one of the deepest images ever -- the
Hubble Ultra Deep Field (HUDF).
The resulting HUDF is like a
jewel box of strange and distant galaxies.
A recent analysis of the
HUDF
focused on the smallest, faintest and most compact galaxies imaged.
These small galaxies are thought to be the
building blocks of
modern galaxies.
Analysis shows that these small galaxies are indeed themselves frequently merging to form large galaxies.
An image of this field with the
Spitzer Space Telescope
shows a lack of
infrared
emission that would be expected from old stars,
indicating that these small galaxies are very young, possibly only a few million years old.
Therefore the young blue stars might be members of the
first-ever generation of stars.
Part of the HUDF is
shown above,
while one blue building-block galaxy, highly
redshifted by the universe so as to appear more yellow,
is shown in the upper left inset.
