A supernova is the explosion of a star. It is the
largest explosion that takes place in space.
Supernovas are often seen in other galaxies.
But supernovas are difficult to see in our own
Milky Way galaxy because dust blocks our
view. In 1604, Johannes Kepler discovered the
last observed supernova in the Milky Way.
NASA’s Chandra telescope discovered the
remains of a more recent supernova. It
exploded in the Milky Way more than a
hundred years ago.
A supernova happens where there is a change
in the core, or center, of a star. A change can
occur in two different ways, with both
resulting in a supernova.
The first type of supernova happens in binary
star systems. Binary stars are two stars that
orbit the same point. One of the stars, a carbon-
oxygen white dwarf, steals matter from its
companion star. Eventually, the white dwarf
accumulates too much matter. Having too much
matter causes the star to explode, resulting in a
supernova.
The second type of supernova occurs at the end
of a single star’s lifetime. As the star runs out of
nuclear fuel, some of its mass flows into its core.
Eventually, the core is so heavy that it cannot
withstand its own gravitational force. The core
collapses, which results in the giant explosion of
a supernova. The sun is a single star, but it does
not have enough mass to become a supernova.
A supernova burns for only a short period of
time, but it can tell scientists a lot about the
universe.
One kind of supernova has shown scientists
that we live in an expanding universe, one that
is growing at an ever increasing rate.
Scientists also have determined that
supernovas play a key role in distributing
elements throughout the universe. When the
star explodes, it shoots elements and debris
into space. Many of the elements we find here
on Earth are made in the core of stars. These
elements travel on to form new stars, planets
and everything else in the universe.

Scientists use different types of
telescopes to look for and study supernovas.
Some telescopes are used to observe the visible
light from the explosion. Others record data
from the X-rays and gamma rays that are also
produced. Both NASA’s Hubble Space Telescope
and Chandra X-ray Observatory have captured
images of supernovas.
In June 2012, NASA launched the first orbiting
telescope that focuses light in the high-energy
region of the electromagnetic spectrum. The
NuSTAR mission has a number of jobs to do. It
will look for collapsed stars and black holes. It
also will search for the remains of supernovas.
Scientists hope to learn more about how stars
explode and the elements that are created by
supernovas.

You do not have to be a scientist, or even have a
telescope, to hunt for supernovas. For example,
in 2008 a teenager discovered a supernova. Then
in January 2011, a 10-year-old girl from Canada
discovered a supernova while looking at night
sky images on her computer. The images, taken
by an amateur astronomer, just happened to
include a supernova.
With some practice and the right equipment, you
could find the next supernova!