earth and space term 2 test Flashcards
define planets
planets orbit stars
orbit our sun (a star)
9 planets
They are always lower mass than the star itself.
define exoplanets
Exo-planets orbit other stars.
They are always lower mass than the star itself.
4000-5000 exoplanets.
define star
massive, luminous sphere of plasma, held together by it’s own gravity.
define double/triple star
stars that appear to “twinkle” and constant change colour in the sky are actually 2 or 3 stars spinning around each other.
define nebula
A cloud of gas and dust in outer space
Some nebulae are the result of stars dying and then exploding.
The Nebula is a lot larger than the star which formed it.
define star clusters
tightly packed groups of stars gravitationally bonded together
found in galaxies
define galaxy
A system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.
define black hole
A region of space having a gravitational field so intense that no matter, radiation or light can escape.
The black circle right is a black hole. The red/yellow part is stars and other matter getting sucked into the black hole.
define the universe
The universe is everything. All of space and time.
Very large.
define main sequence star
A distinctive type of star which fuses Hydrogen into Helium
define red giant
formed when the hydrogen of a medium star runs out
define planetary nebula
is a cloud of gas formed when the helium of a red giant runs out.
define supergiant
is formed when a larger main sequence star’s hydrogen runs out.
They are very hot so they start off as blue stars but as they cool they become redder
define white dwarf
is formed when the gases of a planetary nebula disperse very hot core remains.
very dense
very hot
much dimmer than the red giants
define black dwarf
is the cold dark remains of a white dwarf when it has cooled.
define supernova
A star that suddenly increases greatly in brightness because of a catastrophic explosion that ejects most of its mass.
define neutron star
is a star formed entirely from neutrons.
very dense
Define astronomical unit
one astronomical unit is equal to the distance from our earth to our sun
define light year
a light year is how far light travels in one year and equal to how many years back in time
define parsec
parallax second equal to 3.26 light-years
what is the location of star clusters?
open clusters are mostly in the flat “galactic disc”
globular clusters orbit our galaxy in the “galactic halo”
define characteristics of globular star clusters
More than 50 parsecs in size,
sometimes much more!Spherically Shaped
define characteristics of open star clusters
Less than 5 parsecs in size,
usually much less ! Irregularly Shaped
define the apparent magnitude and two factors that influence it
the measure of how bright the star will appear to an observer on earth
two factors:
- how much light the star emits
- distance between the observer and the star ( smaller distance = greater brightness)
