There’s a wonderful comedic quiz show in the UK called "QI" — for "Quite Interesting" — which is hosted by none other than Stephen Fry. The participants are comedians, and they’re asked questions ranging over just about every topic you can imagine. The BBC recently uploaded a clip about which alert BA Bloggee Brett Warburton informed me. In it, Fry shows the contestants a video of the Sun setting, and asks them to ring in when they think the Sun has completely set. Here’s the clip:
This is, in fact, correct! The Earth’s air bends the image of the Sun upward, so we can still see the Sun even though it is physically below the horizon. If we didn’t have air, daytime would be shorter. In fact, this effect works for sunrise as well, so we see the Sun rise before it’s physically cleared the horizon.
And Stephen was correct in the amount too; the light is bent upward by just about the same size as the Sun, so when the lower limb of the Sun just kisses the horizon it’s actually already set.
But it’s a bit more complicated, of course. Read More
[Note: ROSAT fell to Earth last night; see this post for details and links to more info.]
Time lapse videos can be breathtaking, lovely, and a joy to watch… but they can also show you something you may not have thought about before. Before I even read the caption for Murray Fredericks’ video called "IRIDIUM", I knew it was filmed in the southern hemisphere. Can you guess how?
[Make sure to watch it in HD, and make it full screen.]
If you live in the northern hemisphere — and odds are very good that you do — then you may have noticed the motion of the Sun and stars looked a bit odd. For example, as you watch the Sun set at the beginning of the video, it does so at an angle moving from the upper right to the lower left. The stars do too. When they rise, they move from the lower right to the upper left.
To me that’s backwards!
Imagine sitting in a gossamer structure 100 meters long, 400 kilometers off the Earth’s surface, and hurtling through space at nearly 30,000 kilometers per hour.
Now imagine facing east while doing so, looking out the window, and seeing this:
ISS astronaut Ron Garan took this shot on Saturday morning, August 27, 2011, as the Sun rose over South America… of course, when you see the sunrise, it’s always morning, right? Not necessarily, especially when you outrace the rotating Earth and see 18 such sunrises and sunsets every day*.
Around the same time Ron took this shot, I was getting up to start my own day, and find out just what the Sun can do given a couple of hours to heat up the desert near Yuma, Arizona. Why? Well, without giving anything away, that’s a story that’ll have to wait for a few more sunrises in the future.
[Note: I’m still waiting for more news about the reinstatement of launches to the ISS now that the Soyuz flaw has been found. If there’s some metaphor to be had here with the picture above, feel free to consider it.]
Image credit: NASA
* <pedant>Actually, in the winter at extreme latitudes, the Sun doesn’t rise until afternoon, and may set shortly thereafter. But that’s if you’re stuck here on the surface of the planet.</pedant>
I know this isn’t strictly astronomy, but it’s a lovely time lapse video of sunrises and sunsets in the arctic… and since the Earth is tilted, in the summer the Sun skims just below the horizon as it circles the sky. So hey, I guess it is astronomy related!
You can really see this effect well starting at 1:06 into the video; the Sun sets at a very low angle to the ground, and comes right back up. The sky never gets completely dark.
The video was shot by a man who calls himself Mr. TSO, and he has many other lovely videos on Vimeo. It’s Friday, so take some time and look. You’ll breathe just a little bit easier if you do.
– Gorgeous Milky Way Time Lapse
– Very Large Telescope, Very Stunning Time Lapse Video
– Incredibly, impossibly beautiful time lapse video
– Dust, from the desert below to the galaxy above
– Stunning winter sky timelapse video: Sub Zero
– OK, because I like y’all: bonus aurora timelapse video
– AWESOME timelapse video: Rapture