A dwarf planet a member of the Solar System that doesn’t quite meet the definition of a planet. It is defined as an object that is in orbit around the Sun, that has enough mass for its self-gravity to squeeze it into a mostly spherical shape, that has not cleared the neighbourhood around its orbit, and that is not a satellite. The most famous dwarf planet is Pluto, but others include Haumea, Makemake, Eris and Ceres (which is also the … Continue reading →
An occultation is whenever one object in the sky passes in front of another and temporarily obscures our view of that second object. As enormous as space is, different objects do still sometimes line up and when this happens we say that the nearer object has “occulted” the further one. Most occultations are caused by the Moon – it’s quite large and moves quite fast against the stellar background, so it occults any number of stars every day. Less often, … Continue reading →
Antimatter is just like normal matter, except that the particles that make it up are the opposite versions of the particles which make up regular matter. As you should know, everything physical in the universe is made up of atoms, and those atoms are made of protons, neutrons and electrons. These particles have a number of properties (mass, spin, etc) including charge. An electron has negative charge, and the amount of charge is exactly the same for every electron in … Continue reading →
Dear Urban Astronomer I read your article about black holes and I have some questions:1. Is it possible to protect a space ship from enormous gravitational force from a black hole with a repulsive magnetic field?2. What really happen with a space ship when approaches event horizon.I mean information can pass from this point further why not matter as is our space ship? And where goes the information, in another universe, in another time of our universe or in … Continue reading →
First, a light year is a measure of distance and not time – a lot of people make that mistake. So how far is a light year then? It is the distance that a beam of light travels in a year. Since light moves at a speed of three hundred million meters per second, a light year is quite far: just over 9.46 trillion kilometers. Because that number is simply too big for any human brain to really understand, try … Continue reading →
