Autumn Equinox & Day/Night Terminator

[cwjames]

Hi All,

Today was the Autumn Equinox and as you would expect the length of day and night are the same.

This results in the Day/Night terminator as seen from space, moving accros Australia being parallel with the lines of longitude.

I have capture todays satellie images from the Australia Weather Bureau and made the following gif file to show its movement across Australia.

http://www.cwjames.info/astro/howto/autumn-2008.php

It's even more interesting if you then see how the Day/Night terminator changes between the winter Solstice and Spring Equinox. The Day/Night terminator changes its angle in relation to the lines of longitude. See the second animation below.

http://www.cwjames.info/astro/howto/...pring-2007.php

I know this is simple stuff, but I find it interesting to see this.


Thanks for reading.

Chris

[Dog Star (Phil)]

Many thanks Chris. Yes, it may be simple, but it's more than interesting; it's flaming fascinating. It's thanks to the efforts of blokes like you that makes IIS such a unique and supportive site and gains us MORE than 4000 members.

[Dennis]

Good stuff Chris - thanks. Great website too!

Cheers

Dennis

[Ric]

Well done Chris, a great little movie.

All that cloud looks a bit worrying though.

[cwjames]

Hi Dennis/Ric,

Thanks for the coments.

All this started as a result of looking through the eyepiece at objects in the sky and training the brain to see things from a diferent perspective. I think I was thinking about the Day/Night terminator on the moon for example. My thought process are dominated by logical things and I have to work on the creative processes.

Then I realized I could demonstrate this in a pratical way something !

I made another gif with only two frames, showing the difference Winter/Spring Equinox for the same time of the day. This was most effective at demonstrating how the angle of Day/Night terminator changed with respect to the line of longitude.

I am glad someone else enjoys looking at these.

Se Ya

Chris