In this topic we shall study cosmology. Cosmology is the study of the Universe's origin and the structures the Universe contains.
Great scientists have used observational skills to understand how the cosmos came about. Galileo, Kepler, Copernicus, Halley plus modern day cosmologists like Hubble, Leavitt and Wheeler, not to mention the great Einstein have all contributed to our knowledge of the Universe.
Links to sims on cosmology:
The terms used in cosmology are produced on a pdf on the right alongside a practice sheet. You will learn about black holes and where they are found, what exactly is an exoplanet and an asteroid.
To be in space school you have to be familiar with these terms.
Download the sheets and have some good reading and practice.
Beyond the visible.
We humans can only see the range of electromagnetic radiation in what is called the visible part of the spectrum, for obvious reasons.
But there are a whole range of wavelengths that we cannot see without the aid of different telescopes which are designed for a particular part of the EM spectrum.
The diagram on the left shows that only the visible and radio parts of the EM spectrum reach the ground.
To "see" more we need to go above the atmosphere with our diverse telescopes to gather more data on our Universe.
- Which EM radiation penetrates the least?
- Why is it vitally important that gamma rays don't reach the ground?
Radio telescopes are located on the surface of the Earth. This is because radio waves can travel through the atmosphere to the ground.
Radio waves have the longest wavelength in the EM spectrum. This makes them easy to pass through dust and gas clouds which would block visible light.
Radio waves are valuable in the study of the formation of stars.
Radio telescopes like the Atacama Large Millimetre/sub-millimetre array are arranged in the desert to give great resolution to see planet formation and even black holes.
Check here for more information on what these telescopes have discovered.
Microwaves have shorter wavelengths than radio waves. They can penetrate the Earth's atmosphere but some are absorbed.
Microwave telescopes are very much similar to radio telescopes.
Microwave telescopes such as the Cosmic Background Explorer (COBE) have detected the remnants from the birth of the Universe.
A fabulous picture taken by COBE shows the spread of microwave radiation throughout the Universe.
Find out more about COBE here.
Infrared radiation is emitted by cool objects: Planets, young stars and dust clouds can all be analysed by infrared telescopes.
There is a wide range of infrared wavelengths. Some of these wavelengths can penetrate the atmosphere but most are absorbed by gases such as water vapour and carbon dioxide.
This is why they are mostly located on mountain tops or in dry climates when the water vapour in the surrounding atmosphere is at a minimum.
You can even find infrared telescopes in Earth orbit away from the moisture in the atmosphere. One such infrared telescope is the Spitzer Space Telescope.
You can find out more about what the Spitzer telescope does here.
These telescopes collect and analyse visible light. They are located in high mountains because there is far less turbulent air.
When you look at the stars with your eye you see them twinkle. This is the result of the star's light travelling through the Earth's atmosphere. It is very like when you look up from under the water in a swimming pool and see the lights all shimmering.
Perhaps the most famous optical telescope is the Hubble space telescope. Being far above the turbulent atmosphere it has provided some stunningly clear images of our Universe.
The picture hows the famous Hubble telescope.
Find out more about Hubble here.
These telescopes must be placed above the Earth's orbit because ultraviolet radiation is absorbed by the ozone layer. This is why the ozone layer is vital for all life on planet Earth.
Ultraviolet radiation is emitted from hot objects in the Universe like stars and very active galaxies.
Ultraviolet telescopes like the Galaxy Evolution Explorer gathers UV information from galaxies to study how they evolve and change.
Find out more here about the Galaxy Evolution Explorer telescope.
X-rays are emitted from extremely violent events in the universe.
Neutron stars and black holes spew out vast quantities of X-rays. X-ray telescopes have to be placed above the atmosphere because X-ray radiation cannot reach the Earth's surface.
In 1999 NASA launched the Chandra X-ray telescope. It had to be positioned at an altitude of 139,000 km above the Earth's surface to capture the X-rays.
This altitude is 200 times higher than the Hubble telescope and almost one third of the way to the Moon!
Gamma rays are the most energetic type of electromagnetic radiation. Thankfully they do not reach the surface of the Earth.
Exploding stars such as supernova, neutron stars colliding together and extremely hot streams of gas are among the exotic objects that emit high energy gamma rays.
The Fermi Gamma ray telescope was launched in 2008 and has helped to see the night sky in a totally different light.
Find out about the Fermi Gamma telescope here.
The telescope was named after Enrico Fermi who was a pioneer in high energy physics.