|What is a nebula and is it the first part of the
sun's life cycle?|
|Question Date: 2013-02-19|
Good question! A nebula is a spinning disk-
shaped body of cosmic “dust” and gas, and it
contains the building blocks of a solar system.
Our solar system (the sun and the planets and
smaller bodies) formed from a nebula. I guess
that a nebula can be considered the first stage
of a star’s life cycle, though the star is not
around yet when the nebula first forms. Hydrogen
and Helium are the most abundant elements in a
solar nebula. Gravitational attraction causes a
massive amount of these gases to accumulate in
the center of the nebula. When the ball of gas
(soon to be a star) gets bigger and denser, the
gravitational energy is turned into heat. When
the ball of gas gets hot enough (about 10
million degrees Celsius), hydrogen starts to
convert to helium in a nuclear reaction. This is
a process called hydrogen burning, and this is
the stage that the sun is in now. The sun
probably reached this stage about 1 million
years after the formation of our solar nebula
(Dickin, 2005, and references therein) and has
been going steady for about 4.55 billion years!
Dickin, A.P. (2005). Radiogenic Isotope Geology:
2nd edition. New York: Cambridge University
A nebula is n cloud of gas, plasma, dust, or
some combination thereof, in space. Nebulae with
enough mass can collapse under their own gravity
to become stars - this is how all stars are
born. That said, some nebulae have much less
mass, such as those created by stars as they
die, and they cannot become new stars (by
A nebula is a cloud of gas and dust, from
which by gravitational collapse a star is
A nebula is simply a large body of gas and
dust in the solar system.
Astronomers have identified many different types
of nebulae. Indeed,
one type of nebula, a solar nebula, describes
the collapsing cloud of
gas and dust that leads to the birth of a star.
However, another type
of nebula can be created during other points in
a star's life cycle.
For example, a planetary nebula is the cloud of
dust and gas ejected
from a dying star during its supernova phase.
fun fact: nebula comes from the latin
word for 'cloud'.
Click Here to return to the search form.
Copyright © 2017 The Regents of the University of California,
All Rights Reserved.