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 →
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 →
Newton’s 3rd Law of Motion is the most famous of the three, but also the most misunderstood: For every action, there is an equal and opposite reaction. To understand what it means, place your hand against a wall, and push. You are now applying a force to the wall through your hand, but your hand does not move. Why? Because the wall is exerting a reactionary force against the hand, exactly equal to your force, but in the opposite direction. … Continue reading →
