As the nights draw in and skies get darker we approach the time of year when aurorae become easier to observe, especially at times (like now) of high sunspot activity. But the link between aurorae and events happening on the surface of the Sun is not immediately obvious and was initially deduced only indirectly. Subject … Continue reading What causes aurorae?
Active Reading
Little is made of the fact that the skills required to read a textbook are different from those used when reading a consumer magazine or a work of fiction. The reasons for this difference are the greater density of information and sequencing of concepts that occur in non-fiction publications. As a result, skimming is best … Continue reading Active Reading
The coldest exoplanet ever seen
Most exoplanets (planets that are outside the Solar System) are detected indirectly. Either a temporary and regular dimming is measured as they pass in front of the host star or their orbit causes a wobble that produces a periodic red-shift in the star's spectrum. Only a small number of planets have then gone on to … Continue reading The coldest exoplanet ever seen
Chandra: the Universe as seen in X-rays
Chandra is the unsung hero of space telescopes. Far better known is the Hubble Space Telescope, which is rightly famous for the spectacular images it has produced. But Hubble was only ever intended to be one arm of a four-pronged approach to astronomical observations, another of which is provided by Chandra. Whereas Hubble produces images … Continue reading Chandra: the Universe as seen in X-rays
Why believe in the Big Bang?
It is often said that the reason why we “know” the Big Bang took place is because the Universe is expanding and if time were played backwards then everything would have started from the same point at the same moment in time. That moment, when everything started moving apart, is what we call the Big … Continue reading Why believe in the Big Bang?
Hypothesis and Analysis
When carrying out a practical investigation it is always helpful to know what sorts of results are expected. In other words, before starting an experiment it is a good idea to consider what theory tells us should be the outcome. The predicted findings form the basis of an hypothesis, which is developed by considering an … Continue reading Hypothesis and Analysis
Astronomy and Cosmology
It would be fair to say that whereas astronomy is an observational science, cosmology uses those observations to model the Universe. With this distinction in mind, there are a number of forthcoming events and publications that I think are worth highlighting. First and foremost is next week’s (April 8th) total solar eclipse, which will be … Continue reading Astronomy and Cosmology
The Hertzsprung-Russell diagram
It is obvious that the stars in the night sky differ from one another; some look brighter, some appear larger and some have different colours. One of the earliest ideas was that all stars are the same but they look different because they are at different stages of development: it’s as simple as the fact … Continue reading The Hertzsprung-Russell diagram
Discharge and Fluorescent lighting
The earliest ways of generating light all involved heat, whether that meant setting a fire, burning a pitch torch, lighting a wax candle or heating a mantle using a gas flame. When electricity arrived, thoughts turned from creating light by chemical means to the possibility of using an electric current. Initial approaches still involved the … Continue reading Discharge and Fluorescent lighting
Hideki Yukawa and Meson Theory
How does the nucleus of an atom stay together? Why don’t the positively-charged protons repel each other and cause the nucleus to disintegrate? The early models of the atom imagined solid spheres, perhaps with different sizes, shapes or “colours” distinguishing one type of atom from another. Then came J J Thomson’s discovery of the electron … Continue reading Hideki Yukawa and Meson Theory
Mr Tarrant's physbang 'blog 