Credit: ESA/Hubble & NASA
This image from Hubble’s Wide Field Camera 3 (WFC3) shows NGC 1448, a spiral galaxy located about 50 million light-years from Earth in the little-known constellation of Horologium (The Pendulum Clock). We tend to think of spiral galaxies as massive and roughly circular celestial bodies, so this glittering oval does not immediately appear to fit the visual bill. What’s going on?
Imagine
a spiral galaxy as a circular frisbee spinning gently in space. When we
see it face on, our observations reveal a spectacular amount of detail
and structure — a great example from Hubble is the telescope’s view of Messier 51,
otherwise known as the Whirlpool Galaxy. However, the NGC 1448 frisbee
is very nearly edge-on with respect to Earth, giving it an appearance
that is more oval than circular. The spiral arms, which curve out from
NGC 1448’s dense core, can just about be seen.
Although
spiral galaxies might appear static with their picturesque shapes frozen
in space, this is very far from the truth. The stars in these dramatic
spiral configurations are constantly moving and spinning around the
galaxy’s core, with those on the inside whirling around faster than
those sitting further out. This makes the formation and continued
existence of a spiral galaxy’s arms something of a cosmic puzzle,
because the arms wrapped around the spinning core should become wound
tighter and tighter as time goes on — but this is not what we see. This
is known as the winding problem.
Source: ESA/Hubble - Potw
