Astro2110 – The Solar System

Something that I thought was interesting about the readings was the concept of the speed of light, but more specifically how it applies to space travel. We know, based on looking out into the universe, that the universe is about ~14 billion years old. Obviously this means, that if we were to travel at the speed of light it would take us 14 billion years to get to the edge of the universe (assuming the same size universe when we travel). The next star system, Alpha Centauri, is 4.3 light years away. If we convert that to driving at around 60 mph, it would take 48 million years to do it. Because we are much much much slower than the speed of light, it makes me question our ability to be able to travel outside our solar system without the use of wormholes or some other scientific breakthrough that we would need to make.

As someone who knew very little about anything astronomy related prior to this course, I was enamored by the first two chapters of the textbook. There were a few topics in particular that I had always been curious about but never got the chance to learn about, one of which being how seasons work. I knew that the early went through one full orbit around the sun and that earth goes through a full rotation once per every 24 hours, however, I fell victim to the common misconception outlined in the textbook that seasons happen because of the variations in the earth’s distance from the sun. It’s interested to me that seasons have nothing to do with the distance, but rather, it is the tilt on Earth’s axis that causes sunlight to fall differently on earth at different times of the year, but the sun remains pointed at Polaris throughout the year. For example, in June, the tilt causes sunlight to strike through the Northern hemisphere at a steeper angle and a shallower angle at the Southern hemisphere, causing summer in the north. The beginning of the summer is the maximum solstice, the steepest angle, so it has the most sunlight. 

Another concept I enjoyed learning about was the idea of the celestial sphere. In this sphere, Earth is at the center, the North celestial pole is directly above the earth’s north pole, the South celestial pole is directly over Earth’s south pole, the Celestial equator is the projection of Earth’s equator in space, and the Ecliptic is the path the sun follows. The celestial sphere gives us a good idea of stars that are visible depending on the location you are at on Earth. The stars north of the celestial pole ar circumpolar because they remain perpetually above the horizon, circling (counterclockwise) around the North celestial pole everyday. The altitude of the celestial pole in the sky is equivalent to the latitude, which measures north-south position.

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