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!
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).
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.
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
On Sunday, May 20, the Moon will pass between the Earth and the Sun, creating a solar eclipse.
However, this isn’t your usual event: because the Moon will be at apogee (the farthest point in its orbit), it won’t completely cover the face of the Sun. Instead of the Sun being totally blocked and the ethereal glow of its corona visible, we’ll see an annular eclipse, also called a "Ring of Fire" eclipse. The picture here — from the October 2005 annular eclipse — makes it clear why!
The eclipse begins at 20:56 UTC (16:56 Eastern US time) on May 20, and ends at 02:49 UTC May 21 (22:49 on May 20 Eastern time). Folks on the east coast of the US will not see the entire eclipse (for those on the extreme east coast, the Sun sets before the eclipse starts for that location [UPDATE: here's a good map to show you if you can see it or not, from the AstroGuyz site]), whereas people on the west coast will barely see the whole thing. For me, in Boulder, Colorado, the Sun will set during the eclipse, which I actually think is pretty cool. That means it’ll sink into the Rocky Mountains with the Moon still partially blocking it, which should make for extraordinary photos!
If you want to see the whole eclipse, the farther west you are the better. The western US and Japan have the longest view, as well as seeing the Sun blocked as much as possible; at the peak, about 94% of the Sun will be blocked by the Moon. Mind you, most people will see this simply as a partial solar eclipse, with the Moon crossing the Sun across a chord. But if you’re in a specific narrow path the Moon cuts directly across the Sun, and you may see the Ring of Fire. Check this interactive Google map to see that path. If you are outside the blue lines on that map, you’ll see a partial eclipse, but in between them you’ll see the annular effect. Cities like Albuquerque and Gallup in New Mexico, Reno in Nevada, and Redding in California may have the best American views.
There are many good sites with details. The NASA eclipse site as usual is the first place you should go, with tons of details. Wikipedia has an excellent article with some good graphics and maps as well.
NOTE: There are lots of great, safe ways to view the eclipse. San Francisco’s Exploratorium has a great list. Search Google for "safe eclipse viewing" for more. NEVER LOOK AT THE SUN THROUGH BINOCULARS OR A TELESCOPE unless you really know what you’re doing. Seriously. Even looking at it with your eyes can be dangerous; just wearing sunglasses can actually make it worse. So go to those links to see the best way to do this.
And if you’re looking for a place to watch the eclipse in the states, I might suggest trying a national park. The National Park Service has a list of places with great views!
I’m hoping to take some pictures myself and collect photos taken by others as well. Stay tuned!
Image credit: Sancho Panza on Flickr; Google.
- INSANELY awesome solar eclipse picture
- When the Earth photobombs the Sun
- Moon bites multicolor Sun… from space!
- Last week’s solar eclipse tripled by Hinode
- ANOTHER insanely awesome shot of the solar eclipse?!
- The July eclipse, from 12,000 meters up
So, tonight is the so-called Supermoon, when the Moon happens to be full at the same time it’s at perigee, the point in its orbit closest to the Earth. This makes it somewhat larger and brighter than normal, and that’s getting a lot of attention in the press. I pointed out a few days ago that in reality, you almost certainly won’t notice the difference between this full Moon and any other, mostly because the difference is small, and our eyes and brain are terrible at judging things like that without something to directly compare it to.
I was thinking about this last night as I watched the almost-full Moon rise in the east (which, I’ll add, ironically looked huge due to the Moon Illusion!), and thought of something that might help illustrate this last point.
Imagine you go outside tonight to look at the full Supermoon rising in the east. Imagine also you’re holding a US dime in your hand (if you live in another country, feel free to substitute your local currency, but beware of the math; hang on a minute to see).
Let me ask you this: How far away would you have to hold the dime so that it appears as big as the Moon to you?
A few inches? A foot? (Convert to metric if you wish). Go ahead, guess!
… OK, ready? [Answer is below the fold so as not to spoil it.]
Did you know there was a solar eclipse last week? Probably not, since — due to the geometry of the Moon’s orbit around the Earth — it occurred over Antarctica.
However, it was seen by the Japanese Sun-observing satellite Hinode (pronounced, "HEE-no-day"; meaning "sunrise"). As the satellite moved around the Earth, its viewing angle of the Moon changed, so it saw the eclipse not just once but three times, making for a very odd video of the event:
This change in perspective is called parallax, and besides tripling the eclipse fun, it also manifests itself as a severe curve to the Moon’s motion in the video. If the satellite were hovering over the Earth, it would’ve seen just one eclipse as the Moon slowly moved across the Sun’s face (if it had been over Antarctica at the time). But the satellite orbits the Earth at a height of about 700 km (400 miles), moving at several kilometers per second. That motion is reflected in the apparent path of the Moon in the sky, and so it saw not just one but three eclipses. Something like this happened earlier in the year with another solar satellite, and I have a more a more detailed explanation in a post about that event.
One of the biggest positive aspects of being a space-faring race is the change in perspective we get by seeing things from a different angle… and in this case, it’s literally a continuously changing perspective. It’s a great reminder that the way we perceive the Universe from the Earth’s surface is not the only way to do so, nor necessarily the best way.
Credit: Credit: Smithsonian Astrophysical Observatory
- ANOTHER insanely awesome shot of the solar eclipse?! (an earlier solar eclipse video by Hinode, and very cool)
- An eclipse from space with a two-way Moon
- A Swiftly passing asteroid
- When the Earth takes a bite out of the Sun
When you go outside at sunset, many times you’ll be greeted with spectacular rays of light and shadow stretching across the sky. These are called crepuscular rays, and are caused by clouds blocking the sunlight, their long shadows cast on haze and other particulates floating in our air.
Those rays fan out, spreading away at different angles… but that’s an illusion! The rays are parallel, and I offer this photograph as proof:
[Click to penumbrenate.]
That shot was taken on October 18, 2011, by an astronaut on board the International Space Station as it passed over India. Towering cumulonimbus clouds threw their long shadows back, away from the Sun. Note that the shadows from different clouds are parallel to each other! That’s because the Sun is very far away compared to the distance between the clouds.
Here’s a picture I found on Flickr showing what we see from the ground, though (it’s not of the same clouds, but just a typical display of crepuscular rays). The fanning out of the rays is actually an illusion, caused by perspective! It’s precisely the same thing that makes railroad tracks or long roads appear to converge in the distance. Things farther away look smaller, so the parallel rails of a railroad track appear to get closer together as you look farther away. For railroad tracks you look down to see this; for cloud shadows you look up! Other than that, they’re the same.
So why do the shadows in the first picture look parallel? It’s because the astronaut was looking straight down on the clouds and shadows, so his distance to any part of the shadow was roughly the same; the shadow near the cloud and way downstream (so to speak) were both about the same distance away from him. That negates the perspective effect, and the shadows are revealed for what they truly are: parallel.
Astronauts have said it for years, but it bears repeating: exploring space gives you perspective. And in this case, it’s literally true.
Image credit: NASA; Elsie, Esq.’s Flickr Stream
This is pretty wild: a partial solar eclipse on March 4, 2011 as seen from NASA’s Solar Dynamics Observatory! Watch as the Moon slips in front of the face of the Sun in this video:
Cool! In this far-ultraviolet view, you can see magnetic activity on the Sun’s surface, like arcing gas eruptions and sunspots (which are dark in visible light, but very bright in the UV), and the roiling, bubbling motion as pockets of hot solar gas rise and fall. Then, suddenly, the Moon makes its appearance!
When I first saw this, I was surprised the Moon appeared to reverse direction. But after a moment’s thought I figured it out: parallax! Here’s how it works:
On January 4, 2011, the Moon passed directly in front of the Sun, treating much of Europe, north Africa and western Asia to a total solar eclipse. I saw lots of really interesting pictures from the event, but this has to win for what must be the oddest image:
[Click to penumbranate.]
This was the view using LOFAR, or the LOw Frequency ARray, a radio telescope in the Netherlands. It’s designed to sense radio waves from space in the range of 10 – 250 Megahertz (which encompasses FM radio and TV broadcast signals, interestingly). Lots of astronomical objects emit at this energy. The Sun is not a terribly luminous source, but it happens to be pretty close by, making it bright.
The images show the partial eclipse at 140 MHz, starting at the upper left as the Moon was already leaving the Sun’s disk. By the last image (lower right) it was all over. I had to laugh: it was cloudy in the Netherlands that day and people missed seeing the eclipse themselves, but clouds are transparent to radio waves. In fact, radio astronomers can, in many cases, observe astronomical objects even during the daytime, rain or shine — for a class in grad school, we observed the Sun when there was snow on the radio dish!
I remember, around that same time, staying up all night at the observatory (and sleeping during the day) for two weeks in a row for my Masters Degree. At about the halfway point I was reconsidering my choice of doing optical astronomy. Of course, now we have robotic observatories which observe for you, and deliver the data via email or FTP. It’s a far more genteel way of doing science.
Y’know, I should never deal in superlatives. I said Thierry Legault’s shot of the ISS during the solar eclipse last week was the best picture of it, but now, as amazing as that picture is, I think we’ve found something to tie it: the Japanese solar observing satellite Hinode took this jaw-dropping video:
OK, I’ll say it: Holy Haleakala!
Hinode (pronounced HEEN-oh-day, which I’m telling you because I always say HI-node in my head when I see it) orbits the Earth, and has a near-continuous view of the Sun. When the Moon slipped between us and our star on January 4, Hinode had what might have been the best view. This video was made using images from the X-Ray Telescope, or XRT, and is sensitive to objects at temperatures of millions of degrees — the Sun’s magnetic field routinely generates such energies. You can see the looping material on the Sun, following the arcing lines of magnetism. The Moon is dark at these wavelengths, so it appears black in the video.
The other cool thing is the size difference between the Sun and the Moon. The Sun is roughly 400x bigger than the Moon and 400x farther away, so they look about the same size in the sky. But the Moon orbits the Earth in an ellipse, and can change its distance to us by quite a bit, well over 10% — that means its apparent diameter as seen on Earth can change by 10% too.