Waves And The Universe Flashcards
Why can we see planets
Because they reflect sunlight
What is a galaxy
A collection of stars
What is a light year
The distance light would travel through a vacuum in one year
9.5x10(12) km
How do scientists start looking for signs of life in the universe
With Earth based telescopes or remote sensing techniques because slave exploration is very expensive
What is seti
Search for extraterrestrial intelligence
They’re looking for narrow bands of radio wavelengths coming from out of space
They look for meaningful signals in the space noise
They’ve been going for about 50 years
We constantly emit radio tv and radar into space to see if it’s detected
Scientists are now looking for laser signs in outer space
What do space crafts do
They carry probes and are sent to investigate planets and moons they carry instruments which can continuously record data about the conditions
What do robots do
They can take photos and collect rock and soil samples
Mars Viking Landers used robotic arms to collect soil samples and carried out experiments to see if there were signs of life the ph sent the results to earth to see if they could find any signs of life
What do scientists do when looking for life from other planets
They work out what all of the data means eg by analysing pictures
They also look for comets and asteroids to see if there could be life there
Why do we use space telescopes
So the earths atmosphere isn’t in the way because some waves are absorbed by the atmosphere
It helps to avoid light pollution which makes it hard to pick out dark objects and air pollution can reflect or absorb light coming in from space
They can see objects that are much fainter than can be seen from earth
What could the first telescopes detect
Visible light
They could only see close by objects and some objects aren’t detectable by juts visible
What are x ray telescopes used for
They are the best way to see violent high temperature events like exploding stars
What are radio telescopes used for
In Cygnus A they showed the structure of the Galaxy and how there’s two hot lobes moving apart from each other
They also were used to discover cosmic background radiation
Why are modern telescopes so good
Bigger telescopes give better resolution and can get more light and they have greater magnification which means we can see further into space
They help discover new galaxies which helps scientists discover more about their life cycle
Computers are used to create clearer and sharper images
What are spectrometers
It is a tool used to analyse the light given out by different galaxies
The light is directed through a slit and split into a spectrum
The light from different galaxies created different black lines Called absorption spectra and are caused by different wavelengths being absorbed eg by elements in the stars atmosphere
What do spectrometers show us
What different stars and galaxies are made up of
Each element has its own specific spectrum
Eg the sun has a similar absorption spectra to a hydrogen lamp so it is probably made of mostly hydrogen
What are emission spectra
When spectra have bright lines and are caused by extra light being emitted at those wavelengths
How to make a spectrometer
Cut a 1mm wide slit on one of the box
Make a slit for the cd at a 45 degree angle on the side of the box
Make a hole to look through above the cd
Make sure the rainbow side of the cd is facing the hole you Look through
Hold the box up so it lets light in from a source
What is the life cycle of a main sequence star
Nebula Main sequence star Red giant Planetary nebula White dwarf
What is a nebula
A cloud of dust and gas that forms a star
How does a nebula become a main sequence star
The force of gravity makes the gas and dust spiral together and gravitational energy is converted to heat energy
When the temp is high enough thermonuclear emission happens to the hydrogen nuclei and helium nuclei are formed which give out huge amounts of energy
What is a main sequence star
The heat created by the nuclear fusion gives an outward pressure that balances the force of gravity pulling everything inwards so the star is stable
How is a red giant formed
When the hydrogen core begins to run out the star swells up and it becomes red as the surface cools
How is a planetary nebula formed
The star becomes unstable and ejects it’s outer layer of dust and gas creating a planetary nebula
What is a white dwarf
When the planetary nebula is formed it leaves behind a hot dense solid core which cools down and eventually disappears
