Science Physics P1T2

One way scientists are looking for life on other planets is through lander probes and rovers. Landers touched down own Mars and in 1976, the lander looked for chemical changes in the soil that could be caused by life. Probes orbit planets and take pictures of evidence such as water channels. Rovers can take images of rocks and soil close up and be able to capture every detail of the substance.

Scientists are also looking for/analysing radio waves coming from space, looking for waves that could have been sent by life forms. They are also looking to see if planets release oxygen, as oxygen is released by plants, suggesting life.

Seti is the search for extraterrestrial life and is the name of a serires of projects. Thye analyse radio waves coming from space and look for signals possiblly produced by intelligent beings. However, no messgaes have been found yet.

All the methods have issues. The rovers and lander probes can take photos however, the images could be interpreted in different waays. The most reliable way would be to send someone out there onto planets. However, the current methods allow scientists to find evidence to allow people to go there.

Nebulae- A nebulae is dust and gas including many particles. Stars form when a nebulea is pulled together by gravity.

Protostar- A protostar happens when the pulled together nebulae starts to get more dense and heats up. It can begin to glow. As more and more dust and gas start to pull together the mass becomes higher. This causes the clouds gravitational pull to get stronger and stronger and compresses the material together even more.

Main Sequence- When the temperature and pressure in the protostar gets high enough it forces hydrogen nuclei to fuse together and form helium. The pressures from the hot gases just balances the compression of gravity. When the star is too hot it expands but when the particles get too cold they are pulled back together. This repeats.

Red Giant- When most of the hydrogen is turned into helium the core of the star is not hot enough to withstand gravity and collapses. The outer layers of the star will expand to form a red giant star.

White Dwarf- The star will remain as a red giant for a further billion years. But, the rest of the star would be pulled togetehr by gravity and will collapse to form a white dwarf. No fusion reactions take place here.

Black Dwarf- A black dwarf will form when a white dwarf gradually starts to cool over a billion years.

Difference between a big and small star:

The diffeence comes at the end of a big and small stars life. Rather than a massive star turning into a red giant it becomes a super red giant due to the mass of the star. Then the super red giant will turn into a supernova. Whereas, a small star will go from a normal red giant to a shell of gas to a white dwarf. A big star will either turn into a black hole or a neutron star whereas, a small star will only turn into a white dwarf. A big star is very dense and has a larger mass than a small star.

When you look at stars sometimes they seem to be moving, by looking at the waves they are emitting you can tell if it is moving away or towards you. When a star is moving away from you the waves are in the red part of the spectrum (red shift). If the star is moving towards you the wvaes go into the blue end (blue shift). Doppler belives the universe is expanding from looking at stars and analyzing whetehr they are moving away. When the waves are in the blue end the higher the frequency and the shorter the wavelength whcih suggests the star is moving towards you like with sound waves the noise from them is higher because the frequency is higher.

Infrasound:

• Below 20Hz.
• Used to detect volano eruptions and animal coomuniaction. A tiger uses infrasound to commounicate.
• Equation: Speed=distannce/time.

Ultrasound:

• Above 20 000Hz.
• Used for sonar, fish finding, sea floor mapping, submarine hunting, prenatal scanning and physiotherapy. Bats use it to work out their location and other animals sometimes use it to hunt their prey.

Seismic Waves:

• Two types of waves, S and P waves. P waves are longitudinal and S waves are transverse. P waves pass through liquids and solids S waves only pass through solids. Measured in km/s.

Keywords:

• Epicentre
• Focus Point
• Triangulation

This theory was first suggestes in the 1930's and says the whole universe and all the space matter included, started out as a tiny point of concentrated energy 13.5 billion of years ago. As the universe expanded, gravity caused matter to clump together to form stars.The universe started when a huge explosion took place and spreaded mater across the universe. Gases came together to create clouds. All matter moves out and temperature decreases and stars and galaxies begin to form. It is believed that the universe is still expanding today.

Evidence:

There is more evidence supporting the Big Bang Theory than any other theory. Evidence includes:

- all galaxies are moving further away supporting the idea that the universe is still expanding.

-red-Shift proves that stars are moving away.

-doppler effect proves that you can tell when sounds created in space are moving away as the frequency becomes higher.

-the cosmic microwave background radiation is thought to be the heat left over from the explosion and the radiation left behind.

This theory was first suggested in 1943. It is the idea that the universe is alaways expanding but maintaining a constant average density. A steady state universe has no begining or end in time. The average density and arrangement of galaxies is always the same just getting further and further. Observations since the 1950's have produced a lot of contradictory evidence to this theory.

As the universe expands more matter is created inbetween the old matter which keeps the growth constant. There is no mass temperature change.

Evidence:

-doppler effect.

-red shift proves stars are moving away.

There is not much more evidence to support this theory.

The temperture of the universe is pretty much the same. Same as Big Bang except there is no explosion but matter was pulled apart and keeps in uniform with one another.

We use telescopes to analyse light in space. These telescopes see things through different types of radiation off of the electromagnetic spectrum. The elecrtomagnetic spectrum contains different types of radiation which have different wavelengths and frequencies.

Radio Telescope: Used to detect radio waves coming from space. They are used to detect things in the universe that an optical telescope cannot see. They are used to look at the mapping of neutral hydrogen and in long baseline interferometry ( a technique that astronauts use to obtain resoultion of a large telescope by using multiple smaller telescopes). A radio telescope is Earth based. Discoveries made: Used in 1989 to create an image of the asteroid 4769 castalia. This was the first image of an asteroid. Radio telescopes helped in the discovery of organic molecules in the constellation Serpens. Helped in the discovery of millisecond pulsers in 1983. Used to discover a new theory about the orbit of Mercury in 1964.

Microwave Telescopes: Used to look at dark energy/matter. It can observe space objects in a frequency range between 70 amd 300 GHz. They look at Earth from space; they look at the Amazon River and see the ice caps melting in Alaska. Microwave telescopes can see through dust clouds and gas in space. Discoveries made: The Cosmic Microwave Background in 1965. In 2003 the Microwave Anisotropy Probe helped determine characteristics of the Universe. Microwave telescopes are space and Earth based.

Infrared Telescopes: Used to look ar hurricanes and storms through infrared. Can look at early galaxies and stars. This can help to find out how early galaxies and stars are formed. Used to look at the difference between temperature in planets and stars. You can look at different molecules that absprb infrared radiation. Discoveries made: The discovery of new galaxies and new dwarf galaxies. The discovery of stellar nurseries, where stars are born. The disocvery of stars bigger than the sun which changed the total mass of the Universe. They are space and Earth based.

Visible Telescopes: Used to look at star constellations and other planets such as the moon and Mars. Used to study asteroids and meteors and their suspected movements. Can be used for imagery and spectrometry. You can see black holes and materials that are in space. Look at clouds of dust and gas and can predict what space matter is in them. Can look at the surface and rocks of planets. Discoveries made: The discovery of moon's on Pluto. and the understanding of seasons on Jupiter in 2007. Galileo used a telescope to discover Jupiters' moons and the moons' craters and the heliocentric model. In 1995 the discovery if how the Universe changes.

Ultra-Violet Telescopes: You can better identify what is in a black hole and see how much energy the center of the galaxy has. Can look at gas from stars and at cosmic sources in the Universe. Look at nebulaes and red giants. You can look at star formation and at objects that emit ultra-violet radiation. Discoveries amde: Discoverd star formations in unexpected regions of the Universe and discovered the long 'tail' of Mira Ceti. Discovered supernova remnants and magnetic fields of stars. Space based telescopes.

X-ray telescope: Can look at galaxy clusters, through black holes, supernova remnants, stars and binary stars containing a white dwarf. You can also look at a neutron star. Can detect x-ray emissions from very hot places in the universe. Discoveries made: The first x-ray images of Mars by Chandra X-ray observatory. The Milky Ways' own supermassive black hole, Sagittarius. The detection of galaxies billions of light years away. X-rays come from the sun. X-ray telescopes are space based.

Gamma ray telescope: You can look at supernovae's, neutron stars, pulsers and black holes. You can see different processes happening in the universe. These include comsic ray interactions with interstellar gas, supernova explosions. You can look at the sun. See what the Milky Way looks like in gamma ray. Discoveries made: The fermi telescope has nearly discovered 1800 pulsers. Discovered gamma-ray outbursts from outside the galaxy. Gamma ray telescopes are both Earth and space based.

The Earth is in the Solar System.

Millions of stars are in a galaxy.

The Universe is filled with hundreds of galaxies.

Order of nearest to Earth: Moon, Sun, Neptune, Altair, Andromeda.

Earth has a diameter of 13000km and the Milky Way has a diameter of 1 times 10 to the power of 18 km.