Earth's Moon as seen from the North Pole
The Moon. What a wonderful thing it is. We, as humans, have developed somewhat of a bond to our Moon, and this is understandable. After all, it has a profound effect on life on Earth, most of this is positive, although there are suspicions that there are some effects of the Moon which have lead to less-than favourable outcomes, as we will explore. Read more »
I’d like to share with you my thoughts on day length and where it is headed. First, let’s just refer to Wikipedia’s definition of day length:
“Day length… refers to the time each day from the moment the upper limb of the sun’s disk appears above the horizon during sunrise to the moment when the upper limb disappears below the horizon during sunset. Due to the diffusion and refraction of sunlight by the atmosphere, there is actually daylight even when the sun is slightly below the horizon. The period when it is still somewhat light even though the sun is below the horizon is called twilight.” – Wikipedia
Antarctic sun rise
Today I thought I would write about the Doppler Effect and Red Shift. What are they? Why do they occur? Why do we refer to Red Shift in the field of cosmology and astrology?
Red Shift is the name given to the perceived ‘shifting’ of waves through the spectrum from our perception. It gives us a measure of speed, or expansion, as is often the case. It can also called Blue Shift, and this is essentially the opposite of Red Shift. However, for the purposes of this post I shall refer to both of them as Red Shift unless otherwise stated.
Have you ever noticed the change in pitch when an object passes you at high-speed? Let’s take an ambulance or a Formula 1 car as an example. As it approaches we hear a higher than normal pitch, but as soon as the sound source starts to move away from us we hear a sudden drop in the pitch of the sound emanating from the source. Most people are aware of this phenomenon, but not so many fully understand it. It is useful for us to understand this, as it is almost the same as Red Shift, or at least it shares enough similarities with the Doppler Effect to be very useful towards our understanding of it. The effect I have just described to you has a special name, the Doppler Shift or the Doppler Effect, named after Christian Doppler who first proposed the effect in 1842.
A visual example of the Doppler Effect
It seems obvious at first, the night sky is dark because there is an absence of light. There is an absence of light because the Sun has moved behind the Earth from our perspective as part of the daily rotation of the Earth about its axis. Simple. So why am I asking this question? Well, as you may have guessed, the answer is not as simple as it may at first seem.
We have different understandings or thoughts on the universe, we call these models. Albert Einstein was among those who believed in a static model, one that states that we occupy a static universe, that is to say that it is neither expanding nor contracting, rather that it is infinite and eternal.
If we are to assume this to be true, and also assume that stars are evenly distributed around the universe, then we are still left with our question: “Why is the night sky dark?”. This is known as ‘Olbers’ Paradox’. Why are we left with this question? Read on! Read more »
I hav
e been reading and watching documentaries on space and time over the past few months. I am very interested in some of the concepts that I am presented with. Tonight I have been expanding my understanding of Time and I will share with you some of my thoughts.
Spacetime can be thought of as the combination of space and time into what is called a continuum. We are all aware of the three dimensions within the world we occupy: length, width and depth. Within the realm of Spacetime, time is considered to be a fourth dimension, accompanying the three we already established. Read more »