I’ve posted a lot of stuff about Sunday’s annular eclipse (see Related Links below), and I figured I was done… but then I got a pretty remarkable picture sent to me.

During the eclipse, in northern California, two men sent a small (6 cubic meter) helium-filled balloon up to 90,000 feet (roughly 27 km). Equipped with a camera and an ingenious system that used puffs of gas to orient the payload, they took this pretty amazing shot of the eclipse:

[Click to penumbrenate.]

That’s the Earth on the left (duh), and on the upper right you can see the eclipsed Sun! They used a solar filter to cover half the camera’s view so that they could get the correct exposure for both the Earth and the much brighter Sun.

I really enjoyed reading their story on how they set this up and executed it. I especially liked how they launched, sat around to watch the eclipse itself, then set off to find the balloon once it came back down (shredded after it popped at its lofty apex).

I love stuff like this! Basic equipment, clever people, and a can-do attitude results in something remarkable. Well done!

P.S. My friend and fellow Boulder astronomer Stuart Robbins posted a series of lovely timed sequences from the eclipse that he took in Albuquerque. It’s well worth a click!

[First: CONGRATS to SpaceX for the successful launch of the Falcon 9 and deployment of the Dragon capsule! Everything looked great and things are apparently going smoothly. You can watch the whole thing here, and I'll have more about all this in a little while. Until then, back to your regularly scheduled blog post.]

Over the past couple of days, a lot of people are passing this image around, saying it’s from the eclipse Sunday, taken by an astronaut from the International Space Station:

Here’s the thing: it’s not. It’s actually a lovely piece of artwork done in 2009 by a Japanese artist who goes by the name A4size-ska on DeviantArt.

There are plenty of clues to show it’s not real, if you know where to look. For one, the real eclipse was annular, meaning a lot of the Sun was still seen around the silhouetted Moon. That’s not apparent here. Plus, the bright Earth (and Sun!) would wash out the background stars in a picture like this, so you’d not see them, and certainly not the Milky Way (the fuzzy band under the eclipse in the artwork).

The picture is certainly realistic otherwise! The artist notes he used images from the European Southern Observatory; the Earth and Milky Way are both clearly real shots.

If you’re curious about what the view really looked like from the ISS, then here you go:

Isn’t that awesome? In an earlier post I put that up an image from that video as well as a pile of other eclipse shots (including two more from space). Universe Today has a bunch more, too.

(more…)

So yesterday was the annular eclipse of the Sun, and I held a live impromptu video chat on Google+ about it. I was joined by Pamela Gay, Fraser Cain, Nicole Gugliucci, and Jason Major, and we had a live video feed using astronomer Scott Lewis’s telescope. It was way too much fun! I’ve embedded the video at the bottom of this post.

We asked for pictures, and my Twitter feed overfloweth with them! I’m collecting them to put into a gallery which I’ll have up soon, but until then, watch this incredible video taken by John Knoll in his front yard in northern California:

Isn’t that amazing? What happened is that all the overlapping leaves made thousands of tiny holes that sunlight could poke through. This acts like a lens, focusing images of the Sun through every hole — it’s how a pinhole camera works. [UPDATE: Timothy in the comments below points out that some people were confused by my wording. I can see why; I had started to explain how a pinhole camera works then decided it was too distracting and instead just linked to Wikipedia. I didn't mean the pinhole is a lens, just that you get a sharp picture if you use one. I should've chosen my words more carefully.] You can read about the details of this on Wikipedia. Here’s a similar video, too.

I’ll have the gallery up soon, so stay tuned!

Finally for now, here’s the live webcast recording. I’ll embed it here, but note it took me a long time to get it set up and running. It really gets started at 17:23, and I suggest you skim around to see the cool stuff.

[UPDATE: The hangout's over. Thanks to all who watched! I'll have the YouTube video up as soon as I can!]

I know this is last minute, but I decided to do a live Hangout on Google+ to talk about the solar eclipse. I’ve embedded the video below if you want to watch. If you want to ask questions, go to the link above or send me something on Twitter. If you leave a comment here I won’t see it!

Today’s the eclipse! I’m excited, though our weather here in Boulder has been fairly touch-and-go the past few weeks. I’m hoping for clear skies so I can see it; I got my eclipse glasses in the mail yesterday, so I’m all set. Locally, CU Boulder is holding a viewing in the football stadium! That’s a pretty nifty idea. As a reminder, the eclipse begins at 20:56 UTC (13:56 Pacific US time) on May 20, and ends at 02:49 UTC May 21 (19:49 on May 20 Pacific time).

I have links in an earlier post on where and when to watch (and yesterday I posted about why the "Supermoon" two weeks ago guarantees today’s eclipse being annular).

Observing the Sun during an eclipse can be tricky, since it’s very bright and can damage your eyes. Wikipedia has an excellent article about this. Something I want to make special note of: during the deepest eclipse, when the Sun is blocked the most, is ironically the most dangerous time to look at it with your unaided eye. Your pupil dilates (opens wide), letting in more light, but the parts of the Sun not blocked by the Moon are still just as intense. That makes it easier to damage your eye, so be very careful.

Of course, you shouldn’t look at the Sun with binoculars or through a telescope! That’ll destroy your eyes — literally — so seriously, it’s not recommended. The only exception is if you have the proper equipment designed specifically to view the Sun. Sky and Telescope’s site has a great rundown of how to observe the eclipse safely, including what equipment you can use.

For more on safe observations, check out Mr. Eclipse’s page, where he has a thorough list of how-tos. The websites io9 and for Astronomy Magazine have some good info, too.

Want an optometrist’s opinion? Here you go. Or you can try some of the tricks listed at The Exploratorium.

If you want to photograph the eclipse, again Mr. Eclipse has great stuff, and this You Tube video demonstrates making a Sun filter for your camera out of a Pop Tart bag! That’s not for your eyes; it’s just for taking pictures (and while some websites say it’s OK for cameras, your mileage may vary — and DO NOT USE THIS for binoculars or telescopes because it does not block enough light to be effective).

The picture here is of the Sun from just this morning, taken by NASA’s Solar Dynamics Observatory. It’s just to give you a reference of what the unblocked Sun looks like. There are some good-sized sunspots today, so they’ll provide a pretty contract and a nice background to the eclipse. To get a current picture, go to the SDO site and you’ll see it there (click the drop-down menu under the picture and select "HMI Intensitygram" to get the visible light view).

You can watch the eclipse online, too. Sky and Telescope has some info on that, and as I understand it NASA will have some live feeds on their Sun-Earth Connection site. The Japanese space mission Hinode will be watching the eclipse, too.

Finally, if you want a number of people to be able to see this event at the same time, the best way is to project the image of the Sun onto a wall or screen. Here’s a video with a very simple and clever method that I may try myself tomorrow. All you need is foil and a makeup (or other flat) mirror:

Cool! It’s essentially a pinhole camera with a bigger hole but a longer focal length, so you achieve the same results.

I hope everyone has clear skies and good, safe viewing of this wonderful event!

Image credit: NASA/SDO

I wrote earlier about the annular eclipse happening this coming Sunday. It’s a solar eclipse, with the Moon blocking the Sun, but because the Moon is at apogee — the point in its orbit farthest from Earth — the Moon appears smaller in the sky, so it doesn’t completely block the Sun. We’re left with a ring of solar surface surrounding the Moon, the so-called Ring of Fire.

I got a couple of people asking me why this eclipse is happening at lunar apogee when we just had a "Supermoon", when the Moon was full at perigee (when it’s closest to Earth in its orbit). This is a good question! It’s not a coincidence. In fact, it must happen this way! Here’s why.

First, here’s a drawing of the Moon’s orbit, courtesy NASA:

The Moon orbits the Earth in an ellipse, so sometimes it’s closer to us, and sometimes farther. The ellipticity is exaggerated in the drawing; it’s actually about a 10% difference in distance between apogee and perigee. The Moon orbits the Earth once every 27.3 days, so it takes about 13.7 days for it to go from apogee to perigee — a little less than two weeks.

This is different than the phase of the Moon, which is how much of the Moon we see lit by the Sun. When the moon is between us and the Sun, it’s new: we only see the unlit side. When it’s opposite the Sun in the sky — when the Earth is between the two — the side of the Moon we see is lit, so we say it’s full. There are approximately 8 billion web pages describing how this works; here’s one I wrote. The time it takes to go from full Moon to full Moon is 29.5 days. That means to go from full Moon to the next new Moon takes half that time, or about 14.7 days — a little more than two weeks.

We can only get a solar eclipse when the Moon is between us and the Sun. This happens when the Moon is new (I’ll note in passing that it doesn’t happen every time the Moon is new, because the orbit of the Moon doesn’t align exactly with the Earth’s orbit around the Sun).

The phases of the Moon don’t line up perfectly with its position in the orbit because of the two different periods: 27.3 days to go around the Earth, but 29.5 days to go from full to full again (this video might help you). So sometimes full Moon happens at perigee, sometimes at apogee, and most of the time sometime in between.

Now let’s put this all together! The Supermoon is when the Moon is full and at perigee, right? That’s what happened on May 5th. On Sunday, a bit more than two weeks will have elapsed since then. That means the Moon will have moved halfway around its orbit — it actually reaches apogee on Saturday May 19th. But the phase has been changing, so it’s new on May 20, and it so happens that things have aligned for it to eclipse the Sun.

Since this happens the day after apogee, the Moon is farther away than usual, and from Earth it looks smaller. BOOM. Annular eclipse.

I think the confusion stems from folks not knowing the Moon orbits the Earth once per month on an ellipse, so it goes from perigee to apogee in two weeks. Once you get that, hopefully the rest of this makes more sense.

And because why not, I’ll leave you with this video showing the phase of the Moon as well as its apparent size in the sky as they change over the course of the year. If you want a detailed explanation of what you’re seeing, here ya go.

Enjoy the eclipse! And make sure if you watch it, you do so safely.

Image credits: NASA; Sancho Panza on Flickr.