Newton’s 2nd Law of Motion states that if you apply a force to an object, it will accelerate at a rate proportional to its mass, and to the amount of force applied, and that the acceleration will be in the same direction as the force. We write this mathematically as: F = MA (Force = Mass times Acceleration). This makes sense, because we all know that it is easier to move a light object than a heavy one. A heavy … Continue reading →
Newton’s first law of motion says that an object at rest will remain at rest unless acted on by an unbalanced force. An object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force. What does this mean, in plain english? Every object in the universe hates change: If it’s stationary, it will not just start moving by itself. If it is moving, it won’t change that movement by … Continue reading →
The Delta Aquarid meteor shower is actually two showers radiating from points within the same region of sky, and which overlap on the calendar. The Northern shower runs from July 16 to September 10, peaking on 13/14 August, while the Southern delta aquarids cover the period from July 14 to August 18 and peak on 29/30 July. These showers favour us in the Southern Hemisphere, partly because their radiants are high up in our skies, and partly because they peak … Continue reading →
Dark energy is the name used by scientists to describe whatever it is that is pushing the universe apart. Since the 1920’s, astronomers have been able to see that the universe is expanding, and this knowledge led them to the Big Bang Theory. One of the Hubble Space Telescope’s most amazing discoveries was that this expansion is not slowing down (as you would expect, because of gravitational attraction), but actually speeding up. Nothing that we know about physics can explain … Continue reading →
Dear Urban Astronomer How exactly do satellites work? Who invented them, and how many are up there now? I heard somewhere that there must be millions! Is this true? Yours Curious Dear Curious All artificial satellites have one thing in common: they are in orbit around something (usually the Earth), and will in theory stay up there indefinitely all by themselves. If by “How do they work”, you meant “How do they stay up there”, then prepare for a … Continue reading →
