Copernicus is generally credited with having first described the “true” arrangement of the solar system at a time when Science was being reborn after the Dark Ages. So revolutionary was his book De Revolutionibus that he withheld it for more than 10 years before finally publishing a small number of copies in 1543. As he … Continue reading Kepler: Greater than Copernicus
Mammoth effort to image our galaxy in infra-red
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
What causes aurorae?
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?
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?
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
Balloon on the Moon
Imagine that you could take a helium-filled balloon to the moon. If you stood on the lunar surface, holding the ribbon tied to the bottom of the balloon, what would you expect to happen when it was released? We'll assume that the balloon doesn't burst and I'll give you four possible outcomes; The balloon rises … Continue reading Balloon on the Moon
Star Count 2023
Looking up at the stars is awe-inspiring experience but light pollution from the ground greatly reduces the number of stars that can be seen. Even a single neighbouring security light that is either permanently on or frequently activated by people or animals can ruin the night sky for others. There is an annual event that … Continue reading Star Count 2023
Mr Tarrant's physbang 'blog 