Our Home – the Magnificent Milky Way

I have been wanting to get into amateur astronomy since I was a kid. Something about out vast universe amuses and interest me a lot. It’s so beautiful, so vast, and an infinite amount to explore.

I have found that astronomy is sometimes difficult to get into for me. Although I’m living in the suburbs, there are still plenty of light pollutions around. Not to mention the cost of equipment for something as amazing as what I’m about to show. Ok ok, it’s not that expensive to get into amateur astrophotography, I’m just cheap.

As I was on my nightly crawl on wired one day and came across this amazing time lapse video by Randy Halverson at Dakotalapse.com.

Plains Milky Way from Randy Halverson on Vimeo.

The video depict the Milky Way moving across the sky through the night.

The Milky Way is our home, where our solar system and of course earth is located. The Milky way we see in the sky is actually the rest of our very own galaxy. This is because our solar system is located near one end of the Milky way (in the Orion arm to be more specific), shown below.

Map of our Milky Way Galaxy from [2], Note that the solar system is located near the bottom in the Orion Arm

Since we’re in the Milky way galaxy, we cannot see the top view of the galaxy but rather only the edge on view. The view we get from earth is one that looks toward the center of the galaxy all the way to the other edge, or out of the galaxy on the nearer edge.

The Milky Way we see on Earth spans the sky at different angles depending on the time of night, the season and where you are located. This is because the the plane formed by the elliptical path that the earth travels around the sun (also known as the Eclipitc), is actually not parallel to the galactic plane, the plane that our spiral galaxy lies on. If it was, the Milky way can be seen parallel to the horizon every night of the year. In fact, the ecliptic and the galactic plane actually lies about ~60 degrees incline to the galactic plane [3]. To make things more complicated, the Earth’s own rotation axis (for the rotation that gives us day and night) is not exactly perpendicular to the Ecliptic. The Earth is actually tilted 23.5 degrees from the vertical [4], which is also the reason for the different season we experience.

What all of this tells us is that the angle we see the Milky Way here on earth can change depending on the relationship between which season we’re in (our position along the 60 degrees incline plane), the time of night, and of course the location at which we’re viewing it. So look up when you’re out of the city, and you might be amazed at what you can see.Milky Way as would be seen in Toronto, Canada on June 20, 2011 Midnight if there were no buildings or light pollution at all. Taken with Stellarium 0.10.5 on Ubuntu.

Video: Randy Halverson @ Dakotalapse.com.[1]

Images: Figure 1 from Richard Powell [2], Featured Photo taken with Stellarium 0.10.5.

[1]Randy Halverson (2011), Plains Milky Way [Online], Available: http://dakotalapse.com/?p=368

[2] Richard Powell (2006), A Map of the Milky Way [Online], Available: http://www.atlasoftheuniverse.com/milkyway.html

[3] James Binney and Michael Merrified (1998), Galactic Astronomy, Princeton University Press

[4] Philip C. Plait (2002), Bad Astronomy: Misconceptions and Misuses Revealed, From Astrology to the Moon Landing “Hoax”, John Wiley and Sons


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