Stars go through a number of changes as they pass through different life stages. If a star doesn’t have more mass than about eight times that of our own Sun, then it will end its life as a White Dwarf. White dwarfs are extremely small, hot and compact objects, composed of degenerate matter, and are all that remains after the original star runs out of fissionable fuel and ejects its outer layers into space. What remains is usually around … Continue reading →
“Nebula” is the Latin word for cloud. It was originally used to describe anything in the night sky that had a cloudy or diffuse appearance, and that wasn’t a comet. Early in the 20th Century, however, it was discovered that some of these nebulae were actually “island universes” (galaxies or globular clusters). Since then, the word refers to specific types of objects: Planetary nebulae are usually spherical and are the expanding shells of material ejected from dying stars. They get … Continue reading →
A lack of any convincing evidence, mainly. There have been countless thousands of reports of UFO’s over the last century, but most can be easily explained by natural phenomena or known human activity. For example, the sighting of a mysterious spinning spiral in the sky above Norway turned out to be a malfunctioning rocket spinning out of control. Other cases turn out to be the planet Venus (“There’s something hovering above the horizon, as bright as an aeroplane’s landing lights”), … Continue reading →
Gravity is the force that attracts objects with mass towards each other. On Earth, it is what brings us back to the ground if we jump upwards. In space, it is what makes the Moon orbit the Earth, what makes the Earth and other planets orbit the Sun, and what makes the Sun and stars orbit the centre of the galaxy. According to physicists, there are only four forces in the universe, and gravity is the weakest by a ridiculously … Continue reading →
A supernova explosion is one of the most powerful releases of energy in the universe. When the largest stars run out of fuel and collapse, the implosion of their core rebounds with such power that the resulting explosion outshines entire galaxies for several weeks. All that remains is a tiny dense neutron star, surrounded by an expanding cloud of ultra-hot glowing gas which we see as a beautiful nebula. If the star was particularly massive, then the remains of … Continue reading →
