Hemispheres & the Sky
What do you think this view would look like if you were in the Southern Hemisphere?
If you were in the Southern Hemisphere, the stars would be rotating around the South Polar Axis and our North Star would be below the horizon. The Northern view would look much like the tent above instead of the circular patterns around the agave plant in the previous image.
What if you were standing on Earth’s Equator?
The North Star and the South axis point would be right at the horizon. Both horizons would be huge semicircles and no stars would be seen fully rotating around a single point.
How to find your latitude
Look for the North Star, then count how many degrees it is above the horizon. You can roughly figure that out with your hand. This is the way that people have done it for ages. When navigating by sea, the sailors could easily figure out where they were in relation to North and South by looking for the North Star at night. Figuring out where they were East and West was a bigger problem that confounded them for years, leading to shipwrecks. Part of the solution was the stars.
If you are interested in learning more, read “Longitude: The true story of a lone genius who solved the greatest scientific problem of his time” by Dava Sobel. It is the story of John Harrison and has a mix of sea exploration, science and the night sky… several of my favorite topics.
The Tilted Earth
For more fun, think about the tilt of the Earth at 23.5 degrees as we revolve around the Sun.
This tilt influences how much atmosphere the Sun’s light has to pass through and the length of daylight, giving us our annual seasons of Spring, Summer, Fall and Winter and is why the sun rises and sets at a different time each day of the year.
On the Spring side of the Solstice, the Sun rises about a minute earlier and sets about a minute later, making each day a bit longer. On the Fall side, the reverse happens and the days get shorter.
Keep an eye out for the upcoming Summer Solstice, this year it will be June 20th. The Sun will set the furthest North on the horizon and we will have approximately the longest day of year.
After that, the Sun begins it's journey southward on the horizon until the Winter Solstice and then heads North again.
Go out one evening to observe where the Sun sets on the horizon and what time it sets, take a photo with your camera or phone.
Return to that same spot a month later at sunset and take another photo, then compare the two.
Did you see a change in the location of the Sun and the time stamp?