Astronomers working on the European Southern Observatory's (ESO's) Visible and Infra-Red Telescope for Astronomy (VISTA) have today published the biggest ever dataset of infra-red images of the Milky Way. A few of the images captured by the ESO VISTA project. Full details about this composite can be found at https://www.eso.org/public/images/eso2413a/ Importantly, capturing images using infra-red … Continue reading Mammoth effort to image our galaxy in infra-red
More than meets the eye
Optical illusions aren't part of the school science curriculum - but they should be. We tend to believe what we see, and a lot of what we know about science is based on visual observations, but we aren't normally taught to question the evidence of our own eyes. One of the classic puzzles of astronomy, … Continue reading More than meets the eye
Energy Budget
It is well known that darker surfaces heat up faster than lighter surfaces and reach a higher maximum temperature. But why? When the maximum temperature is achieved, there is a state of thermal equilibrium that is is due to a balance between the rates at which (new) energy is being absorbed and (previously) stored energy … Continue reading Energy Budget
EM Waves: Uses and Dangers
Different EM waves are used for different applications, which you are expected to be able to recall and explain. We will go through some of these uses in this article, which is unavoidably long as there is a lot of information to cover. Your exam preparation should therefore involve making summary notes from the wealth … Continue reading EM Waves: Uses and Dangers
Surface Colour and Cooling
In the same way that surface colour affects the rate at which objects heat-up and the maximum temperature that they reach (as discussed here) so too will the surface colour affect the rate of cooling. As before, there is a standard experiment that you are expected to know and a typical set of curves that … Continue reading Surface Colour and Cooling
Surface Colour and Heating
Most people say you shouldn't go out on a summer's day wearing black because you will get too hot. It would be much better to wear white as this will keep you cooler. But is that actually true? We can test this idea using two boiling tubes that have been sprayed to have different surface … Continue reading Surface Colour and Heating
Light and Heat
It is obvious to say that hot objects emit (give off) both visible light (a glow) and heat (that we can feel but not actually see). This is true of bonfires, light-bulbs and even our Sun. The connection between heat and light is taken completely for granted in everyday life: the glow of a hot … Continue reading Light and Heat
Using the EMS to Observe Earth
When we look down on the Earth from an aircraft, we are observing the surface of the planet using visible light in a qualitative way - which means that we are simply sensing (seeing) rather than measuring the amount of light reflected. By using instrumentation, we can extract much more meaning from our observations by … Continue reading Using the EMS to Observe Earth
Telescopes in Space
Why do we put telescopes in space? The reason is not to get "closer" to the things we are trying to observe! Although the Earth's atmosphere extends much further, we generally think of space as starting about 100 km above the Earth's surface (see here for more details) and that's a tiny distance compared even … Continue reading Telescopes in Space
Electromagnetic (EM) Waves
Electromagnetic (EM) waves are a family of different types of waves that have some specific properties in common; they all propagate (travel) at the same speedthey are all transverse wavesthey can all propagate through free space without the need for any medium The most common examples of EM wave are the various colours of visible … Continue reading Electromagnetic (EM) Waves
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