Here's my effort ..
Group 1
The Questions are....
1. What is Dark Matter?
From measurements of the mass of the Universe, we are led to the conclusion that most of the matter in the universe is dark. That is, most of the matter cannot be detected from the light which it emits, or doesn’t emit.
This is “stuff” which we think cannot be seen directly. Its presence is believed, (or theorized), to explain the rotation of stars, galaxies, and galaxy clusters/superclusters. If the theory is correct, as a consequence, dark matter can generally only make its presence known through its gravitational effects on known matter (ie: ‘normal stuff’).
It is also required to explain how the matter in the very early stages of the Universe, clumped together and became more dense, eventually forming the really big Universe objects mentioned above, that we see in the universe today.
2. How is Dark Matter formed?
So far, we only have dark matter ‘candidates’. As such, we can only explain the formation of matter we understand, and matter we have directly observed.
‘Neutrino particles’ are one of the dark matter candidates (for example).
In general, neutrinos are formed as a result of certain types of radioactive decay or nuclear reactions such as those that take place in the Sun, in nuclear reactors, or when cosmic rays hit atoms.
Neutrinos were first produced in a nuclear reactor in a 1956 experiment, by the radioactive decay process called ‘beta decay’.
Dark matter candidates are usually split into two broad categories, with the second category being split into two other categories:
Baryonic Dark Matter: matter made up of neutrons, protons and electrons … just like any of the known ‘normal’ matter chemical elements;
Non-Baryonic Dark Matter:matter not made up of neutrons, protons and electrons, and thus unlike any of the known chemical elements.
Of these ‘non-baryonic’ types, there are two main sub-types:
-Hot dark matter: These particles would move at fast speeds, and have higher pressure. The foremost hot dark matter candidate particle is the "neutrino."
Neutrinos travel close to the speed of light, are electrically neutral, and are able to pass through ordinary matter almost undisturbed. This makes neutrinos extremely difficult to detect. Neutrinos have a very small mass (weight).
- Cold dark matter: These particles would move at slow speeds and thus, would have little pressure. We know very little about this category of dark matter. It is however, the most likely candidate for the majority of what forms our universe.
3. How was Dark Matter discovered?
Dark matter was made up, (theorised), by scientists, in order to explain other observations, (see the answer to question 1 above).
Because dark matter can only make its presence known through its gravitational attraction on known matter, we can see its influence on things like the rotation of galaxies etc. Another way of discovering it is examine how light is bent due to the gravity, caused by dark matter’s influence. Evidence for this exists in observations of galaxies (especially elliptical galaxies) which distort the light from other objects behind them, in our line of sight.
4. Where other than space can Dark Matter be found? (If there is no other places, leave blank.)
Nuclear reactors: for the ‘neutrinos’ type candidate.
In space, dark matter can explain the bending of light, (as discussed in the answer to question 3 above), and the constant rotation of galaxies.
5. How has science made an impact on Dark Matter?
Scientific theory effectively invented dark matter as a candidate to explain other observed phenomena in the Universe.
There is much research going on at the moment to identify other candidates. Particle colliders such as that at CERN in Switzerland, may uncover some more candidates. Other research includes observations of the timings of light signals emitted by objects in space and comparing them with what we’d expect to see. If the measurements aren’t as expected, this could provide more clues.
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Group 2
1. What are solar storms and what affect can they do to Earth?
Solar storms are caused by massive ‘flare-ups’ in the Sun’s atmosphere. Generally speaking, there are three main types:
Solar flares: a large explosion in the Sun's atmosphere;
Coronal Mass Ejections: a massive burst of solar wind, associated with solar flares;
Geomagnetic Storms: the interaction of the Sun's outbursts with Earth's magnetic field, causing Auroras, (coloured lights usually only seen at night, close to the Earth’s North and South Poles).
2. What is Dark Matter made of? (Is it nothing or a certain substance)
Dark matter candidates are usually split into two broad categories, with the second category being split into two other categories:
Baryonic Dark Matter: matter made up of neutrons, protons and electrons … just like any of the known ‘normal’ matter chemical elements;
Non-Baryonic Dark Matter:matter not made up of neutrons, protons and electrons, and thus unlike any of the known chemical elements.
Of these ‘non-baryonic’ types, there are two main sub-types:
-Hot dark matter: These particles would move at fast speeds, and have higher pressure. The foremost hot dark matter candidate particle is the "neutrino."
Neutrinos travel close to the speed of light, are electrically neutral, and are able to pass through ordinary matter almost undisturbed. This makes neutrinos extremely difficult to detect. Neutrinos have a very small mass (weight).
- Cold dark matter: These particles would move at slow speeds and thus, would have little pressure. We know very little about this category of dark matter. It is however, the most likely candidate for the majority of what forms our universe.
3. What is the most likely cause of the end of the world and why?
There are several possibilities. Here are some of the more likely:
(i) The Sun’s expansion at the end of its Hydrogen burning stage, will eventually engulf the Earth, heating it up to the point where the oceans will evaporate off into space. (This won’t start happening for about another about 5 billion years, though .. so don’t worry too much about it at the moment .. there’s plenty of time left to save ourselves !)
(ii) Collision with Andromeda Galaxy (In about 4.5 billion years). This may not necessarily cause the end of the Earth’s existence however. We may just get pushed to another location in the Galaxy, or we may not move anywhere. The outcome is not yet clearly known;
(iii) Being zapped by a huge ‘Gamma Ray Burst’ from a source we can’t see yet. (This also, could happen anytime, or it may not happen at all). It hasn’t happened over the Earth’s 5 billion years of existence.
Overall, the most likely ‘end’ is likely to be item (i) above. This is because it is a scientifically predictable outcome.
4. Is our Solar System large?
A good way to think of the size of our Solar System is to think about how long it might take to get to the outer edge of it. For example, how long does it take to get to Pluto ?
The answer is: It takes a long time for a probe to get to Pluto. The ‘New Horizons’ spacecraft, headed for Pluto, was launched on the 19th January, 2006. It had an velocity of about 16 km per second (59,000 km per hour), after its last engine shut down. Thus, it left Earth at the fastest launch speed ever recorded for a man-made object. It flew by Jupiter on the 28th February, 2007, and Saturn's orbit on the 8th June, 2008. It will arrive at Pluto on the 14th July, 2015, and then will continue into the Kuiper belt.
So, that’s about 8 years travel time just to get to Pluto, for the fastest spacecraft ever launched ! (Pluto is about 6 billion kilometres from the Sun).
The Kuiper belt is about the farthest distance at which solid objects exist in our solar system, and is about 6.3 billion kilometres from the Sun.
The Solar Wind however, goes out even further is about 24 billion kilometres from the Sun. The Sun’s gravity is thought to dominate objects out to 6,000 billion kms, although scientists are not exactly certain of this.
The Solar System is just a dot compared with the Milky Way Galaxy. (Try this link to get a feeling for the size of it all
http://htwins.net/scale/).
5. How long should Earth last?
The Earth should last for about another 5 to 6 billion years until the outer parts of the Sun expands close to the Earths orbit. The Sun’s expansion at the end of its Hydrogen burning stage, will eventually engulf the Earth, heating it up to the point where the oceans will evaporate off into space. (This won’t start happening for about another about 5 billion years, though .. so don’t worry too much about it at the moment .. there’s plenty of time left to save ourselves !)
6. Where would be our next home after Mars and Europa?
Other candidate places where life might be able to exist are Enceledus or Titan, both of which are moons of Saturn.
Enceledus might work because it is thought to have water oceans below a layer of thick ice. Life needs water and there may be usuable water under the ice. We know there’s water there, though because it has been detected in ‘geysers’, by the Cassini probe, which is patrolling out there at the moment.
Titan may also be another candidate, because it is has an atmosphere thought to resemble Earth’s very early atmosphere. It also has ‘land’ and ‘lakes’ (of a chemicals called ‘methane’ or ‘ethane’). Life evolved here on Earth, when we had a similar atmosphere, so it may also evolve on Titan.
Cheers
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