Space Physics Flashcards
Galaxies
Collections of billions of stars orbiting around a galactic centre (black hole)
Star
Ball of gas (hydrogen and helium) which radiate energy in the form of electromagnetic wave
The sun
An average star in the Milky Way, halfway through its lifespan, which emits infrared, ultraviolet and visible light
Nuclear fusion in a stable star
Hydrogen atoms join together with enough force to fuse into helium atoms. This reaction produces a lot of energy which is released in the form of electromagnetic waves
Nuclear fusion in older stars
Old stars run out of hydrogen, so start fusing other things together and becomes unstable
From where a star is born
Interstellar clouds of gas and dust of which hydrogen must b present in
When is a star considered a protostar
When, due to gravity, the interstellar clouds start to collapse upon themselves causing all the elements to clump together. Hydrogen nuclei start fusing together and gravity pulls in more materials causing the temperature to increase
How can astronomical distances be measured
In light years where one light year is the distance travelled in the vacuum of space by light in one year.
9.5 x 10^5
Life cycle of a star (8)b
-Star formed from interstellar clouds of gas and dust containing hydrogen
-protostar forms due to the cloud collapsing and increasing in temperature due to its internal gravitational attraction
-Stable star forms when the inward force of gravity is balanced by an outward force due to the high temperatures
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Describe what the solar system contains (5)
One star, the sun
8 planets mvemjsun
Minor planets, dwarf planets (Pluto) and asteroids in the asteroid belt
Moons that orbit the planets
Smaller solar system bodies (comets + natural satellites)
What are seasons caused by
Solar rays are more concentrated over a smaller area in the summer than in the winter
Comets
Clumps of loosely bound rock and ice moving in highly elliptical orbits around the sun
Orbits of the planets and comets etc.
They have elliptical orbits, of which the sun is not the centre unless when the orbit is approximately circular. When an object is closer to the sun it is faster as gravitational potential energy is converted to kinetic
What does the gravitational field strength of a planet depend on
It’s mass
Compare the first 4 planets to the last 4, why are they different
First 4 are rocky and small, last 4 are gaseous and large
The accretion model for solar system formation
Accretion model
4.5 billion years ago:
-Interstellar clouds of gas pulled together by gravity
-Planets formed in the accretion disk formed, through the rotation of material in the cloud, as the dust and gas comprised of many elements came together
When there was enough mass in the sun:
- Huge amount of energy produced that blew lighter particles from the planets to the outer parts of the solar system, resulting in the inner planets having a higher density than the outer
Why planets orbit the sun
As the sun contains most of the mass in the solar system. This means that the sun has a very strong gravitational attraction which keeps the planets in orbit
Describe the sun referring to size, composition and energy radiation
Star in the galaxy called the milky way
Medium size
Hydrogen and helium
Infrared, visible and ultraviolet regions of the electromagnetic spectrum
What are stars powered by
Nuclear reactions that release energy
What Nuclear reactions in stable stars involve
The fusion of hydrogen into helium
Galaxies
Consist of billions of stars
Describe the distance between the earth and the sun and other stars in the Milky Way
The earth is closer to the sun than the other stars
How can astronomical distances be measured
In light years (distance traveled in the vacuum of space by light in one year)
9.5x10*15
Light year
Distance travelled in the vacuum of space by light in one year
9.5x10*15
Redshift
Increase in the observed wavelength of the electromagnetic radiation emitted from receding stars and galaxies
Diameter of the Milky Way
100 000 light years
The universe
Made up of billions of galaxies
Describe Light emitted from distance galaxies
Appears redshift in comparison to light on earth, is evidence of the universe expanding and supports the Big Bang theory
CMBR
Cosmic Microwave Background Radiation
Microwave radiation of a specific frequency observed at all points in space, produced shortly after the universe was formed and expanded into the microwave region of the electromagnetic spectrum as the universe expanded
How can the speed at which a galaxy is moving away from the earth be found
The change in wavelength of the galaxy’s starlight due to red shift
How can the distance of a galaxy be determined
From the brightness of a supernova in that galaxy
How can the distance of a galaxy be found
Using the brightness of a supernova in that galaxy
Hubble constant
Ratio of the speed at which the galaxy is moving away from the earth due to its distance from the earth
H0=v/d
Current estimate for bubbles constant
2.2x10*-18 per second
What does
d/v=1/H
Represent
An estimate for the age of the universe
Evidence for the idea that all matter in the universe was present at a single point
