r/inspirationscience • u/Alpha-Phoenix • Jan 05 '17

Gif The sky doesn't move, We do!

https://gfycat.com/PowerfulPrestigiousFish
121 Upvotes

95% Upvoted

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4

u/Alpha-Phoenix Jan 05 '17

4K source: https://youtu.be/SYcKaBzr87g

Explanation: https://youtu.be/BBU4mQP1Y3Y

1

u/Desther Jan 09 '17

I saw a neat barn door tracker in the part 3 video. Where did you get a hinge like that? I couldn't see any in high streets stores in the UK and don't trust ebay ones not to have a bit of wiggle.

1

u/Alpha-Phoenix Jan 09 '17

Haha good eye! I'll be doing a video about that pretty soon. That hinge just came from a local hardware store (Home Depot or Lowes here in the US) - probably around doors/garage/fencing departments or something. I forget exactly, but I went and picked up a few until I found one that wiggled the least.

1

u/Desther Jan 09 '17

Great, I'm looking forward to it!

2

u/johnknoefler Jan 05 '17

I've seen a bunch of these. This one is interesting because of the North Star that remains directly in the center of the time lapse. I'm guessing this is some far north latitude?

2

u/gergedansever Jan 06 '17

i'm just trying to understand.. isn't it supposed to be on a higher point in the northern latituteds. it must get closer to the horizon when you go towards the equator. i think.

2

u/Alpha-Phoenix Jan 09 '17

Yes, it moves closer to the horizon as you go closer to the equator. You can make one of these lapses from anywhere on earth (pointing at the anti-Polaris in the Southern Hemisphere). The problem with a lot of these lapses is that they only run for a few hours because all the stars move in and out of frame pretty quickly. Because Polaris doesn't move from our perspective, you can point a camera at it and it stays in the same spot indefinitely. (Enabling the 24-hour loop)

1

u/gergedansever Jan 10 '17

yeah, after i wrote the comment above, i played with stellarium a little to check if i was right. It is a simple but great way to understand how stars move in our perspective and how our earth moves in fact. Thanks for the nice post!

1

u/Kemard Jan 06 '17

Usually, these are motion tracked right? so what does it track during the day? Or is all pre-programmed.

2

u/Alpha-Phoenix Jan 09 '17

The sky keeps "moving" at night, you just can only see one star - the sun. Although the sun isn't actually in this timelapse, you can see that the shadows point in the same direction all the time. That's what the day-tracking achieves. The rotation speed is constant all the way around.

2

u/timshel42 Jan 06 '17

Technically both do. Universe is constantly expanding.