P1 - The Earth in the Universe Flashcards
What is the Solar System made up of?
- EIGHT Planets (including Earth) that orbit the sun in elliptical orbits.
- Moons - small masses that orbit the planets.
- Asteroids - small, rocky masses that orbit the Sun.
- Comets - small, icy masses that orbit the Sun.
- Dwarf planets - Small spherical objects that have not cleared their orbits of other objects.
How old is the Solar System?
4.6 billion years old.
How was the Solar System formed?
- Started as clouds of DUST and GAS, which were pulled together by the FORCE OF GRAVITY until the whole cloud started to collapse in itself.
- At the centre of the collapse, particles came together to form a protostar. When temperature got high enough, NUCLEAR FUSION started. This made the Sun.
- The remaining dust and gas formed smaller masses, which were attracted to the Sun.
In general, how many galaxies are roughly present? How many stars do they contain?
Thousands of millions of galaxies, each containing thousands of millions of stars of stars (The Sun is one of the stars in the Milky Way). All of these galaxies make up the Universe.
From smallest to largest, recall the relative sizes of objects within the Universe.
- Diameter of the Earth
- Diameter of the Sun
- Diameter of the Earth’s orbit
- Diameter of the Solar System
- Diameter from the Sun to the nearest star.
- Diameter of the Milky Way
- Diameter of the Milky Way to the nearest galaxy.
Where does all the evidence that we have about distant stars come from?
The RADIATION astronomers can detect.
A lot is shown when studying Electromagnetic Radiation it emits, e.g. the colour the star appears shows its surface temperature.
Light travels at very ____ but ____ speeds.
Light travels at very HIGH but FINITE speeds.
What is the speed of light in km/s IN A VACUUM?
300 000 km/s
What is the unit that measures vast distances in space?
LIGHT YEARS (ly)
What is a light year?
The distance light travels in one year ( 9500 billion km)
What does the finite speed of light mean?
That very distant objects are observed as they were in the past, when we the light we see now left them.
What are the two methods that astronomers use to work out the distance to different STARS?
- Relative Brightness
2. Parallax
What is Relative Brightness?
The dimmer a star is, the further away it is.
However stars can vary in brightness so we’re not 100% certain
What is Parallax?
When something appears to move when you look at it from different positions.
How long does it take to measure the two different positions of an object in parallax?
6 Months
What is the issue of Parallax with very distant stars?
The further away the star is, the more difficult and less accurate the measurement is.
What can interfere with the observations of the night sky?
- LIGHT POLLUTION
2. ATMOSPHERE
Why did scientists put the Hubble Space Telescope in space?
To avoid certain problems such as light pollution and other atmospheric conditions.
Where does the Sun’s energy come from?
NUCLEAR FUSION - Hydrogen fuse together to make helium (a heavier nuclei).
All chemical elements with a larger mass than helium were formed by…..?
All chemical elements with a larger mass than helium were formed by NUCLEAR FUSION IN EARLIER STARS.
When a galaxy is moving away from us, what happens to the wavelength? What is this motion called?
The wavelength of the light from it changes. The light becomes REDDER because the light has SHIFTED to the red-end of the Electromagnetic Spectrum.
This is called RED-SHIFT.
By seeing how much light has been red-shifted, what can we work out?
How quickly a galaxy is moving away from us.
The _______ the red-shift, the ______ it’s moving away from us.
The GREATER the redshift, the FASTER a galaxy is moving away from us.
The more ______ the galaxy, the _____ it’s moving away from us.
The more DISTANT the galaxy, the FASTER it moves away from us.
Because galaxies are moving away from us, what evidence does this provide in terms of the Universe?
This provides evidence that the whole Universe is expanding.
From youngest to oldest, rank the ages of the Earth, Sun and the Universe.
- Earth (4500 million yrs)
- Sun (5000 million yrs)
- Universe (14 000 million yrs)
What do scientists believe happened when the Universe was born? Why do they think this?
The Universe started with a huge explosion. This is because the fact that galaxies are moving away, they must’ve moved from a single point.
What does the Universe’s ultimate fate depend on (2) ?
- How fast it’s expanding.
2. The total mass there is in it.
If there is enough mass compared to how fast the galaxies are currently moving, the Universe will eventually….?
The Universe will eventually STOP EXPANDING and then BEGIN CONTRACTING. This is called the BIG CRUNCH!
If there is not enough mass in the Universe to stop the expansion, the Universe will….?
The Universe will keep expanding.
Why is it difficult to predict the fate of the Universe?
- We can only measure the mass of those parts of the Universe which emit RADIATION.
- Precise measurements of the speed and distance of the galaxies is difficult because their radiation travels such a LONG WAY to get to us.
What are the 4 types of evidence that rocks provide for the change of the Earth?
- EROSION
- SEDIMENTATION
- FOSSILS
- FOLDING
What is erosion?
The changing of the surface of the planet over long periods of time. Material erodes slowly from mountains and becomes sediments which make rocks.