Nicola Davis - Stunning Hubble Bubble Nebula image marks telescope's 26th birthday
The space telescope celebrates its
anniversary on 24 April; this spectacular image of a cloud of gas and dust
8,000 light years away celebrates the occasion.
It looks like a giant,
glistening, soap bubble blown into the night sky. In reality, it’s a cloud of
gas and dust 10 light-years across that exists around 8,000 light-years away in
our Milky Way galaxy. Known as the Bubble
Nebula, the wispy-looking shell surrounds an off-centred star whose mass is
more than ten times that of our sun. The plasma thrown out by this star, its
so-called stellar wind, is responsible for forming the “bubble”, while its
intense radiation causes the gas to glow.
The Bubble Nebula, also known as NGC 7653, captured by the Hubble
Telescope. Photograph: Nasa/ Esa/ Hubble Heritage Team
The bubble itself is
composed of interstellar material as well as gas and dust from the nearby giant
molecular cloud, that can be seen to the top, left of the image - also glowing
from the star’s radiation. While the bubble is currently expanding at the
astounding pace of 100,000 km an hour, this giant molecular cloud will
eventually put the brakes on its growth. “The cloud gets denser and denser as
you get to closer to its centre, so at some point the cloud will be too dense
for the weaker and weaker solar wind to push even further,” explained Mathias
Jäger of the European Space
Agency.
Composed of four
images captured by the Hubble Space Telescope earlier this year, the picture
has been released to celebrate the 26th anniversary of the
instrument’s launch on 24 April. While the Hubble has previously captured
the Bubble Nebula, this is the first time a full picture has been created from
its images. “If you compare [the
new picture] to the earlier images you would see some very, very small
changes,” said Jäger. “Nothing spectacular for the lay eye, but for astronomers
it is enough to see how the gas behaves inside the bubble.”
