Over the next several weeks, skywatchers will thrill to a couple of astronomical wonders playing out in daytime skies: a solar eclipse on May 20 — and then, on June 5, a "micro-eclipse" of the sun that involves the planet Venus.

As senior staff scientist at San Francisco's Exploratorium, Paul Doherty will be keeping a careful eye on both of those wonders (with appropriate eye protection, of course). He'll let you in on his eclipse-chasing secrets on Wednesday night during a "Virtually Speaking Science" chat on BlogTalkRadio and in the Second Life virtual world. I'll be the host for the hourlong show, starting at 9 p.m. (6 p.m. PT/SLT).

Doherty says the solar eclipse and the micro-eclipse will be well worth chasing.

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"By all means, go out of your way to see 'em," he told me this week. "They are rare events ... You'll have things to talk about for years after."

Each event offers a special kind of rarity: This month's eclipse is of the annular variety, which means that the moon's disk isn't quite big enough to cover the sun completely. At its darkest, the moon's black circle will be surrounded by a spectacular "ring of fire." That sight can be seen only along a narrow track running along Earth's surface, from China across the Pacific to the western United States. But a partial solar eclipse will be visible across a much wider swath of territory. It'll take about three and a half hours for the moon's umbral shadow to race across Earth's surface, from 6:06 to 9:39 p.m. ET.

Next month's micro-eclipse, more formally known as a transit of Venus, is even rarer. The planet's tiny black disk will march across the sun over the course of several hours (roughly from 6 p.m. ET June 5 to 12:50 a.m. ET June 6). Most of the world will get in on at least part of the show, but the best viewing will be had once again from the Asia-Pacific region. This will be the last transit of Venus most of us will ever get a chance to see: The next one is due in the year 2117.

Even if you're not in the viewing zone, or the skies are cloudy, you can still get in on these events via online presentations that will be sponsored by a variety of organizations — including the Exploratorium, of course. The combination museum and science center is planning a webcast of the transit as well as a Second Life teach-in timed to coincide with the annular eclipse. Doherty will be in on all the action — in Nevada for the eclipse, and at San Francisco HQ for the transit.

Over the past 40 years, Doherty has been chasing astronomical events in locales ranging from Cape Cod to Zaire. In this first of two postings about the coming attractions, Doherty discusses the appeal of eclipses and transits, plus a little bit of the science behind them. Here's an edited transcript of the Q&A:

Cosmic Log: You've been in on a number of solar eclipses in your time — what is it that draws someone to become an eclipse-chaser? A lot of people talk about how sun-observing satellites have come so far that eclipses aren't as crucial for scientific observations as they used to be. So what's the appeal?

Paul Doherty: It's certainly true that an eclipse is not a scientifically significant as it was a century ago, but I will tell you there's something special about the experience of an eclipse — even a partial eclipse. You'll be outdoors, looking around, and you'll notice that the light is getting very strange. There's a beautiful clear sky, and it starts to get dim. Your body knows that something really different is happening. It's great for people to know what's causing that feeling: The moon is blocking the sun. (But don't look at it directly with your unprotected eyes.)

Then, for totality, you have the experience of seeing a clear sky go dark at midday, so that the brightest planets and stars are visible. You see that black disk where the sun should be, surrounded by bright rays like big fat spider legs of white around the sun. That will set the hair on your back standing up, even if you're a scientist and you know what this is. It is just so awesome to see it.

So I look at modern eclipses as places for people to come in contact with a great event in our solar system, and it shouldn't be missed.

Q: Do you find that it's an inspirational experience? Do eclipse-chasers go on to "harder drugs" in astronomy?

A: I've met so many eclipse-chasers who are already into the harder stuff. You just can't tell which came first. But I'm sure that the sight of a total eclipse just inspires them. I've seen eight solar eclipses myself, and I keep running across the same people. I know that they're inspired to really take time out of their lives, and take money out of their bank accounts, and invest it in these few minutes of a great experience, surrounded by an hour of interesting shading in the sky, surrounded by days of travel to wonderful places on Earth and meeting people with the same passion they have.

Q: What are the differences between a total solar eclipse like the one in November, and an annular eclipse like the one this month?

A: The moon is in an elliptical orbit around the earth. When the moon is at its farthest point from the earth, its angular size in the sky is a little smaller, and when it's close to the earth, it's a little bigger. Also, the earth is in an elliptical orbit around the sun. It gets smaller and bigger. When the moon is farthest from the earth, it's small enough in the sky that it cannot totally block the bright part of the surface of the sun called the photosphere. That's where the bright light comes from on the sun. At that point, the rim of the photosphere shines around the edge of the moon. That light is so bright that it can damage your eyes if you look at it without eye protection. It overwhelms the dim light coming from the chromosphere and the corona of the sun.

But during a total solar eclipse, the moon is big enough in angular size to block out the photosphere completely, and with your naked eye you can see this million-degree gas glowing in the corona, like rays reaching out quite a ways from the sun. You can see the red chromosphere quite near the edge of the moon. You can even see prominences reaching out from the sun and moving during the course of the eclipse. The total eclipse offers many more things to see than the annular eclipse does.

However, an annular eclipse provides you with a bright circle of the sun. Let's say that sunlight is streaming through the leaves of a tree, and you look at the ground. Normally, you'd see round circles of light at your feet. During an annular eclipse, those all become the letter "O." That is really something, to look at the ground underneath a tree and see it covered with bright Cheerios.

If you're not on the center line of annularity, and it's a partial solar eclipse, then those images become the letter "D," or a really nice letter "C."

There are more total solar eclipses than there are annular eclipses, because it takes this special combination of the moon being a little farther away from the earth than average, and the sun a little closer, to create this annular eclipse opportunity.

Q: It seems as if people in the know are getting as excited about next month's transit of Venus as they are about the eclipse. Why is that?

A: Well, the transit of Venus is a much rarer occurrence. And it is kind of a micro-eclipse. Venus is one-thirtieth the diameter of the sun in angular size, and it's moving across the sun's disk in this stately procession that lasts six hours. It happens in this amazing pattern: There'll be one transit, and then eight years later there'll be another one, and then it's 121.5 years, then eight years, then 105.5 years. It's a really weird pattern.

You wouldn't even notice a transit was happening unless someone told you. The light on the ground is not going to change. You're not going to see anything. But it's different if you know it's happening, like Jeremiah Horrocks did in 1639. He noted that Johannes Kepler, his hero, missed the calculation that Venus was going to transit the face of the sun. Horrocks actually set up a telescope to project the sun's image into his darkened room, and became the first person ever to see a transit of Venus and record it.

Now, knowing what we do, we can tell you that on this day, at this time, if you project an image of the sun safely or use a sun-viewing filter, you can see this tiny black disk going across the face of the sun. That's interesting — but what's really interesting is that in 1761, they used the transit observations to measure the size of the solar system. Good old Halley, of Halley's Comet, figured out how to do that. They did it kind of roughly, during transits.

Q: And even today, astronomers are using alien transits to learn about new planets beyond our solar system...

A: That's right. In 1761, a Russian astronomer named Mikhail Lomonosov discovered the atmosphere of Venus during a transit. He noted that as Venus approached first contact with the sun's disk, it was completely surrounded by a bright glow, which was the sunlight being refracted by Venus' atmosphere and being sent to Earth. That's how scientists first detected Venus' atmosphere. And during the transit eight years ago, scientists used the sunlight going through the atmosphere of Venus to measure its composition.

We're doing that exact same thing with exoplanets. We're studying the light going through the atmosphere of those exoplanets, and we've actually found the constituents of the atmospheres of some of those exoplanets. They've found water vapor, and carbon dioxide, and sodium gas. We're using the very same techniques we used on Venus to study the air of exoplanets.

On Wednesday, we'll talk about some of the best places in America to see this month's annular eclipse, how to pick out an advantageous viewing spot near you, and how to make sure you see the eclipse and the transit safely. Then, be sure to tune in "Virtually Speaking Science" on BlogTalkRadio or in Second Life — and bring lots of questions. Paul Doherty (a.k.a. Patio Plasma) and I will be at the StellaNova Small Auditorium, courtesy of the Meta Institute for Computational Astrophysics, starting at 9 p.m. ET (6 p.m. PT/SLT) on Wednesday. If you miss the live event, don't worry: It'll be archived by "Virtually Speaking" on BlogTalkRadio as well as iTunes.

On Friday, head on over to the Cosmic Log Facebook page for our weekly "Where in the Cosmos" picture puzzle. If you're the first to solve the riddle, you'll be eligible to receive a pair of sun-viewing safety glasses for this month's eclipse and next month's transit. In the meantime, check out these podcasts from previous episodes of "Virtually Speaking Science," plus links to eclipse-related resources:

• Veronica Ann Zabala-Aliberto on spaceflight and Yuri's Night
• JPL's Dave Beaty on the search for life on Mars
• Shawn Lawrence Otto on science and politics
• Ig Nobel impresario Marc Abrahams on silly science
• Rocket scientist Robert Zubrin on Mars exploration
• Propulsion expert Marc Millis on interstellar spaceflight
• Sean Carroll on the puzzling frontiers of physics
• Rand Simberg on the private-enterprise vision for spaceflight
• Martin Hoffert on the future of energy policy
• George Djorgovski on science in virtual worlds
• Alan Stern on suborbital research and NASA's mission to Pluto
• Col. 'Coyote' Smith on the outlook for space solar power
• Tim Pickens on rocket ventures and the Google Lunar X Prize

More about eclipses:

• Interactive graphic: What causes a solar eclipse?
• 12 must-see skywatching events in 2012
• All about solar eclipses on msnbc.com

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Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter or adding Cosmic Log's Google+ page to your circle. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for other worlds.

Millions of people witnessed today's total lunar eclipse, and that means there were plenty of cameras snapping in the darkness. We've put together this sampling from the photos submitted via FirstPerson, Facebook, Google+ and Twitter.

This was the last total solar eclipse until 2014, but there'll be plenty of other sky phenomena between now and then — including an unusual "diamond ring" annular solar eclipse next May, a Venus transit in June, a total solar eclipse in November, and meteor showers galore. Please keep us in mind whenever you've got a cool picture of the cosmos, and thanks for passing along slick eclipse pics like these:

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This eclipse preview story provides further explanation of the "impossible" selenelion phenomenon (alternate spelling is "selenehelion"). While we're on the subject of selenelion, toy inventor Mark Burginger sent in a couple of photos from the parking lot at Tetherow Golf Course in Bend, Ore., that shows the eastward sunrise view as well as the westward lunar eclipse view.

Follow the links below to see eclipse photos from:

• C.J. Cassarino of Livermore, Calif.
• Dale Cunningham of Corona, Calif.
• Barbara Hewitt of San Marcos, Calif.
• Joe Leonard of Taos, N.M.
• Fran Pepoon of Roseville, Calif.
• Anthony Wells from Hawaii

Thanks again to these photographers as well as others who submitted eclipse pics. For still more about today's event and other eclipses, check out these links:

• PhotoBlog gallery of lunar and solar eclipses
• Interactive: What causes a lunar eclipse?
• Nine cool facts about the lunar eclipse
• Why an eclipse paints the moon red

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Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

Did you catch today's total lunar eclipse? Take a good, long look at these pictures of the dusky dark moon: It'll be more than two years before we see a fresh batch.

The best seats in the house for today's spectacular were in Asia. A lunar eclipse occurs when the moon is positioned just right in its orbit to pass through Earth's shadow. Today, that occurred when Asia and the Pacific were facing right at the moon. Other regions of the world, including some areas of Europe and the western U.S. and Canada, could catch at least part of the show before sunrise or after sunset. Here's a sampling of the snapshots:

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I watched the onset of the eclipse's total phase from our deck, east of Seattle, but the clouds closed in partway through the 51-minute window of totality. Did you see the moon's red glow? Leave a comment below, and if you captured a great picture, point us to it and we just might add it to the roundup.

So if it's a total eclipse, why didn't the moon go totally dark? The lunar surface takes on that dusky appearance during a total eclipse because some sunlight is refracted around Earth by our planet's atmosphere. It's as if the glow of a thousand sunsets is directed toward the moon. This report explains the physics that's involved.

Although there'll be some partial eclipses of the moon in 2012 and 2013, our next dose of lunar eclipse totality won't come until April 15, 2014. But next November, a total solar eclipse will be visible from a narrow track that stretches across northern Australia and the South Pacific. Stay tuned for that one ... and in the meantime, check out these links to eclipse pictures and lore:

• PhotoBlog gallery of lunar and solar eclipses
• Interactive: What causes a lunar eclipse?
• Nine cool facts about the lunar eclipse
• Why an eclipse paints the moon red

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Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

The calendar may say there's a full moon, but millions of people will be watching for the moon to go dark on Saturday, during the last total lunar eclipse until 2014. And even if you can't see the eclipse in the sky, you can still bring it up on your computer.

The best views will be available in Asia and the Pacific, but the western U.S. and Canada will get in on at least some of the action. In fact, there's a chance that Westerners could see an "impossible" eclipse, with the dark moon and the rising sun in the sky simultaneously.

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Lunar eclipses occur when Earth is positioned in its orbit just right to cast a huge shadow on the moon. Unlike a total solar eclipse, which can be seen only along a narrow track of Earth's surface, a lunar eclipse can be seen by half the world. You do have to be in the right half, however.

The show begins with a faint penumbral dimming of the lunar surface at 6:33 a.m. ET Saturday, and reaches its climax at 9:06 a.m. ET with the start of totality. By then, of course, the sun will be up on the East Coast, but folks on the West Coast should be able to see the dark moon over the western horizon. This map from Sky & Telescope can tell you what to expect:

If you're getting up early to see the show, there's no need to get up too early. But you will want to keep an eye on the moon during the 10 or 15 minutes before the onset of totality. That's when you'll see the perceptible darkening of the lunar disk as Earth's shadow creeps across.

The moon doesn't go totally dark during totality. Some sunlight is still refracted by Earth's atmosphere, giving the face of the moon a  sunset glow. The precise shade (reddish? brownish? orangish?) depends on the character of the dust and the clouds in the atmosphere. For example, total eclipses tend to be very dark after big volcanic eruptions, as explained in this guide from eclipse expert Fred Espenak.

Over at the NASA Science website, Tony Phillips points out that Saturday's eclipsed moon may look unusually huge to the North Americans who can see it, due to the "moon illusion." It's not that the moon gets bigger when it's near the horizon; it's just that our brain is programmed to perceive sky phenomena differently depending on whether they're overhead or lower down in the sky. This archived article from 2008 explains how it works.

The total phase of Saturday's eclipse is due to last 51 minutes. For North Americans, sunrise and moonset could come before that time, depending on where you live. On the other side of the world, some folks in Europe, Africa and the Middle East will see only part of the show after sunset. In between, most Asia-Pacific observers will be able to watch the whole thing, while South America is out of luck.

But then there's the Internet: Even if you're totally out of the eclipse zone, or facing total cloud cover, you can still experience totality on your computer screen. A remote-astronomy service called Slooh is offering a live eclipse feed from Hawaii, Asia and Australia starting at 8 a.m. ET (5 a.m. PT), with audio narration by astronomer Bob Berman. He'll be joined by several guests and will also take call-in questions. You can use a Slooh app to watch the show on your Android phone, or click on this window:

Here are some other webcast options. If you come across any I've missed, please let me know about them in your comments below; I'll add them to the list if appropriate:

• Hong Kong Observatory: The view from Hong Kong's skies.
• SWAN: The view from Siliguri in the Indian state of West Bengal.
• Univ. of North Dakota: 3 minutes of totality from Grand Forks.
• WPBT2: Florida public TV presents webcast from Reno, Nevada.

If you snap a picture or capture a video of the eclipse, will you please share it with us? Feel free to use our FirstPerson upload tool, or post it to Facebook, Flickr or YouTube and let me know about it via the Cosmic Log Facebook page. We'll put together a smorgasbord of eclipse pics on Saturday.

It'll be a while before we see such a sight again. Only partial or penumbral lunar eclipses are expected during 2012 and 2013. Our next date with lunar totality comes on April 15, 2014. Don't worry, the world won't end: It'll just seem like it on Tax Day.

More about lunar eclipses:

• Interactive: What causes a lunar eclipse?
• Nine cool facts about the lunar eclipse
• June eclipse turns the moon into a star
• Why an eclipse paints the moon red
• The 12 stages of the total lunar eclipse
• How a lunar eclipse saved Columbus
• A lunar eclipse ... as seen from space

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Don't forget to send along the pictures you want to share by following the instructions above.

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

Today was "Black Friday" for some folks in southern climes, and not because it's the big shopping day after Thanksgiving: A partial solar eclipse made the sky just a little bit darker in areas of New Zealand, Tasmania, South Africa and Antarctica.

Some observers spotted only a slight grazing of the sun, while others — such as Williams College astronomer Jay Pasachoff and his eclipse-chasing colleagues — could see the moon take an appreciable bite out of the sun's disk in the skies over Invercargill in southern New Zealand. "After an in-and-out, off-and-on-rain day, we are very pleased," Pasachoff said in a report from Sky & Telescope's Kelly Beatty.

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Pasachoff passed along another perspective on the eclipse, taken from the seventh-floor offices of the New Zealand Department of Conservation in Invercargill. The hand in the picture belongs to Steve Butler, who works for the government agency.

"I gave him one of my solar filters to hold so I could take that photo (Nikon D200)," Pasachoff told me in an email. "He is the regional project manager and was able to grant us access to that site where we were shielded from the wind ... aside from the fierce wind that came through the opened window."

Antarctica's researchers had what were potentially the best seats in the house, with up to 90 percent of the sun's diameter blacked out. Unfortunately, it doesn't sound as if the weather was all that cooperative down at the bottom of the world.

Today's event was the last of four partial solar eclipses during 2011, but there's one more eclipse to close out the year. A total lunar eclipse will be visible from half the world on Dec. 10-11, with best viewing available from Australia, Asia and the Pacific. North Americans will see the beginning stages of the eclipse, while Europeans and Africans will catch the ending.

Next year brings a new crop of solar spectacles, including an annular "ring" eclipse visible from Asia, the Pacific and the western U.S. on May 20, and a total solar eclipse visible from Australia and the South Pacific on Nov. 13. 

More eclipse treats:

• Solar eclipse dims skies in Europe, Middle East
• Marvel at the 'Midnight Sun' eclipse
• The sun gets double-crossed
• Eclipse views turn moon into a star 

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Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

If you're in North America, you may have had no idea that an exceptional lunar eclipse took place this afternoon. But most of the rest of the world got in on the spectacle, and you can, too, after the fact.

This eclipse was notable for several reasons: The moon went right through the center of Earth's shadow, which means the total phase went on for 100 minutes — the longest duration since the year 2000. Also, last week's volcanic eruption in Chile was thought to have put enough sulfur in the air to lend a dusky, coppery color to the moon during totality. The reddish shade certainly didn't disappoint, as you can see in these pictures.

 

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Every total lunar eclipse bring the question, "Why does the moon turn red?" And we have the answer: It's because the reddish wavelengths of the sun's blocked light are actually bent around Earth's disk, lending a sunset glow to the eclipsed moon.

 

Phases of the eclipse were visible from wide swaths of Africa, Europe, Asia, Australia as well as the Indian Ocean and South America. Pretty much every major land mass in the world, in fact, except for North America and Greenland. If you're hankering to see a total lunar eclipse with your own eyes, the next opportunity comes on Dec. 10, when the show will be visible from the U.S. West Coast as well as Australia, the Pacific and most of Asia.

More about eclipses:

• Interactive: What causes a lunar eclipse?
• Nine cool facts about lunar eclipses
• Greatest hits from a partial lunar eclipse
• Marvel at the 'Midnight Sun' eclipse

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You can connect with the Cosmic Log community by "liking" the log's Facebook page or following @b0yle on Twitter. Also, give a look to "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

A solar eclipse at midnight? Putting those two terms together doesn't normally compute, but this week's partial solar eclipse was a rare and lovely exception. The moon's shadow blotted out part of the sun's disk over far northern areas of the world, where the sun is above the horizon long into the night. The "midnight sun" wasn't the only weirdness about this eclipse: How many celestial events do you know that begin on a Thursday and end on the previous Wednesday?

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The image above was captured by Bjørnar G. Hansen from the island of Kvaløya, near Tromsø in the Norwegian Arctic, just before midnight. The sunbeams, clouds and the outstretched hand add to an already-charming image. Tony Phillips of SpaceWeather.com, which attracts a gold mine of pictures showing auroras, eclipses and other sky phenomena, rates it as one of his favorites.

Bernt Olsen watched the eclipse from nearby, at Brensholmen, and got some good shots of the eclipse despite rain and clouds. "There are 73 years to next time we will experience something like this here up north in the Arctic," he said in his note to SpaceWeather.com. Three of his pictures are below, and you can see more of them at Olsen's Flickr and Facebook pages.

Svetlana Kulkova captured early-morning views of the eclipse from the Siberian city of Bratsk. On the night before the eclipse, the skies were obscured by clouds as well as smoke wafting over the city from nearby forest fires. "But the clouds dispersed during the night, and the sun only had to break through the fog and the smoke," she wrote on the Astro-Bratsk.ru website. Here's a picture of the sun glowing red over the city:

ChinaFotoPress sent along these views from Changchun in China's Jilin Province:

One of the weirdest views of this weird eclipse was sent in to SpaceWeather.com by B. Art Braafhart from Salla in the Finnish region of Lapland. "Nice to get a reaction about this wonderful nature moment!" Braafhart told me in an email. "I have received many positive reactions already." Dutch National TV is featuring a selection of his images, which follow the sun all the way down to the horizon during the eclipse. My favorite of the bunch would have to be the picture below, which shows the sun's "cat eyes" just before the last wedges of sunlight blink out. What a way to finish up an eclipse gallery!

More about eclipses:

• Interactive: What causes a solar eclipse?
• Gallery: Greatest hits from solar eclipses
• January's partial solar eclipse amazes skywatchers
• PhotoBlog: Did you see the total eclipse of the moon?

Update for 1 p.m. ET June 7: Check out this time-lapse video of the eclipse, as captured by Eivind Kolstad from Norway. "Most of the world will never experience the midnight sun eclipse," Kolstad writes. "Scandinavia is the only densely populated area in the world where the midnight sun eclipse can be experienced."

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To see the extent of this week's eclipse, and why it was so weird, check out this chart from Fred Espenak's NASA eclipse website, plus this animated image tracking the moon's shadow. We can look forward to four more eclipses this year — including similarly weird partial solar eclipses on July 1 and Nov. 25, and total lunar eclipses on June 15 and Dec. 10.

You can connect with the Cosmic Log community by "liking" the log's Facebook page or following @b0yle on Twitter. Also, give a look to "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.