Another astronomical event: View the ‘Venus Transit’
Posted: Tuesday, May 29, 2012 5:22 pm
Tribune
On the heels of this month’s annular eclipse, the East Valley Astronomy Club and Gilbert Rotary Centennial Observatory welcomes guests to experience next week another unique astronomical event: the Venus Transit.
The Venus Transit is when Venus passes in front of the sun. Venus will only block out about 3 percent of the sun, but the event will be visible thanks to telescope solar flares. The Venus Transit will not repeat again for more than 100 years (2117).
Families are invited to the Riparian Preserve at Water Ranch event June 5. Beginning at 3 p.m., the Venus Transit will be viewable until sunset, scheduled for about 7:30 p.m. A $3 donation is requested.
For more information, visit riparianinstitute.org/observatory.cfm.
Venus Transit Of Sun On June 5 Called Rare Scientific Opportunity
Posted: 05/30/2012 8:09 am Updated: 05/30/2012 8:09 am
By: Clara Moskowitz
Published: 05/29/2012 02:03 PM EDT on SPACE.com
Scientists are gearing up for the upcoming transit of Venus, an extremely rare opportunity to watch the planet Venus pass in front of the sun as seen from Earth.
Venus is due to make this cosmic crossing June 5-6 — the last time such an event will occur until 2117.
When viewed through special solar filters or protective equipment, the transit should offer skywatchers and amateur astronomers an unforgettable sight, weather permitting. But the event is also a rare opportunity for scientists.
As Venus transits the sun, sunlight will be filtered through the planet's atmosphere. By analyzing the absorption features in this light, researchers can learn more about the chemical elements present in the gaseous haze around Venus.
Many of the world's premier telescopes will be trained on the sight, including NASA's Hubble Space Telescope and Solar Dynamics Observatory, as well as the European Space Agency's Venus Express satellite in orbit around Venus.
The Venus Express science team will be watching, and broadcasting live, from the Arctic island of Spitsbergen.
"We're very excited about watching the transit from such a unique European location while Venus Express is in orbit around the transiting planet," Venus Express project scientist Håkan Svedhem said in a statement. "During the transit, Venus Express will make important observations of Venus' atmosphere that will be compared with ground-based telescopes to help exoplanet hunters test their techniques."
Because of the peculiarities of the orbits of the planets around the sun, Venus transits are visible from Earth in pairs separated by eight years. The upcoming transit is the second in a pair that began with one in 2004, which at the time was the first visible in more than 121 years. [Venus Transit of 2004: 51 Amazing Photos]
The 2004 transit provided scientists with the first opportunity to view such an event with modern equipment and telescopes.
"Modern solar telescopes captured unprecedented view[s] of Venus’s atmosphere backlit by solar fire," astronomer Tony Phillips wrote on the Science@NASA blog. "They saw Venus transiting the sun's ghostly corona, and gliding past magnetic filaments big enough to swallow the planet whole."
While scientists are excited for this year's Venus transit, they don't stand to learn quite as much as their counterparts did in the 18th century, when a pair of Venus transits in the 1760s have been described by modern historians as "the Apollo program of the 18th century," according to Phillips.
Then, astronomers had no way of measuring the absolute size of the solar system, until the Venus transits presented an opportunity to triangulate the distance to Venus by comparing measurements made from different vantage points on Earth. Scientists spread far and wide around the planet — famous explorer James Cook went to observe from Tahiti — however, bad weather and technical glitches prevented measurements of the accuracy scientists had hoped for.
Now, researchers will be able to observe the transit with an accuracy 18th-century scientists could only dream of. In addition to studying the planet Venus, scientists plan to use the transit to test techniques they hope to wield studying alien planets beyond our solar system.
Planetary transits are a key technique used to detect extrasolar planets, as these planets subtly dim the light of their parent stars when they pass in front, thus signifying their presence. Not only can researchers discover alien planets by searching for signs of these transits, but just as with Venus, they can learn about the planets' atmospheres by looking at the absorption features in the parent stars' light.
"During next month's transit, astronomers will have the chance to test these techniques and add to the data collected during only six previous Venus transits observed since the invention of the telescope in the early 1600s," according to a European Space Agency statement.
You can follow SPACE.com assistant managing editor Clara Moskowitz on Twitter @ClaraMoskowitz. Follow SPACE.com for the latest in space science and exploration news on Twitter @Spacedotcom and on Facebook.
Everything you need to know about next week’s Transit of Venus
On Tuesday/Wednesday June 5/6, Earth will have the best seat — the only seat — for a great show: the Transit of Venus across the face of the Sun. This is a relatively rare event, and the next one won’t happen until December 10, 2117, so I’m guessing this will be the last time you’ll be able to see it.
I have a lot of info below, so I’ve broken it up into sections. Also, a special note: Fraser Cain, Pamela Gay, and I are hosting a live online video chat star party for the transit! That live video feed will be embedded here on the blog at the time of the transit, so if you read this blog — and you do — you’ll see it. I’ll have more info closer to the date.
Oh — you can click on the pictures here to embiggen them and get more info, too.
What Is the Transit?
A transit is when one object in the sky passes in front of another. In this case, we’ll see Venus move across the Sun’s face. Think of it as a mini-eclipse.
Venus orbits the Sun closer in than we do, taking about 225 days to circle it once. We don’t see a transit every time, though, because its orbit is tilted slightly (by about 3°) to the Earth’s, so most of the time it passes near the Sun, but misses it*. Only when the planets align just right do we see an actual transit.
The geometry works out in a funny way. Transits come in pairs 8 years between events, but each pair is separated from the next two by more than a century. The last pair was 1874/1882. The next transit after that was in 2004. Now we have the second of our current pair, and then the next two won’t be until 2117/2125!
I saw the last transit in 2004, and it was pretty awesome. Venus was just a small dot, barely a disk, seen in silhouette against the Sun, but it was clearly not a sunspot even without magnification. I’ll note here you shouldn’t observe the Sun without eye protection! I have more about that in the Observing the Transit section below.
Historically, the transit was used to measure the size of the solar system. In the 1600s, the distances to the planets were only known in units of the Earth’s orbit. So Venus was 0.7 times as far from the Sun as Earth, and Jupiter was 5 times as far. But the actual size of Earth’s orbit wasn’t known! Before we had space probes and radar (which we can use to bounce signals off planets and measure their distance directly) it was hoped the transit of Venus would allow it to be measured. It worked, but the details are pretty cool and well worth a read. The story is actually told pretty well on the Wikipedia page.
Even in modern times, transits are useful. We look for planets orbiting other stars using a similar method, watching for a dip in the light as the planet blocks the star. To help refine this method, astronomers will use Hubble (!) to look at the Moon (!) — since the Moon is lit by the Sun, the tiny drop in sunlight during the transit should dim the Moon a bit. They’re actually hoping to see if they can detect Venus’s atmosphere too, since that will affect how the light gets to the Moon from the Sun. Amazing.
Interestingly, as seen from Saturn in December 2012, Venus will transit the Sun as well, and astronomers are hoping to use Cassini to see if they can detect it. Also, in 2014, Earth will transit the Sun as seen from Jupiter! Hubble may be used to observe Jupiter at that time to see if it can be detected as well. [Thanks to BABloggee Garrett Curley for this info! You can read more about these space observations at Physics World - you have to register, but it's free.]
* [Actually, because the Earth is moving around the Sun as well, after one complete orbit Venus still has to "catch up" to the Earth to line up with the Sun again. That's called the synodic period, and it takes about 584 days. Still, the tilt of Venus's orbit means it doesn't always cross the Sun directly every synodic orbit.]
So I wanna see it! What do I do?
Because Venus is transiting the Sun, it has to be daytime during the transit for you to see it (duh). The transit occurs from about 22:00 June 5 to 05:00 June 6 (UTC; subtract 4 hours for Eastern US time). The exact time depends on where you are on Earth; NASA has a list of times for US cities and for the rest of the world.
For a more general overview, here’s a map of where the transit is visible:
Places in white see the whole event. Light grey areas see either the first part of the transit with the Sun setting during the event, or the last part of the transit because it’s already in progress during sunrise. Areas in dark grey don’t get to see it at all (sorry eastern South America and western Africa; but you can watch it online!). Since the transit ends at 01:00 Eastern US time, the Sun sets before the transit ends, and the farther west you go the more of the transit you’ll see.
If you look, what will you see? The Sun is 115 times wider than Venus, but Venus is much closer to us than the Sun is (about 42 million km versus 150 million — 25 versus 93 million miles). Because of that, Venus will look to be about 1/30th the Suns diameter, just big enough to see as a tiny disk by eye (but DON’T LOOK AT THE TRANSIT UNPROTECTED; see below).
This is an illustrative animation of what the 7 hour transit will look like. The Sun probably will have sunspots visible during the transit, but Venus will be darker and rounder than they are.
OBSERVING THE TRANSIT SAFELY IS INCREDIBLY IMPORTANT. While looking at the Sun won’t necessarily cause permanent or total blindness, it’s not a good idea, and you should NEVER look at the Sun through binoculars or a telescope unless they are outfitted properly. If you don’t know what you’re doing with astronomical equipment, the best bet is don’t do it.
However, there are many ways to observe the transit safely. In fact, observing the transit is pretty much the same as observing a solar eclipse, so the same rules apply. I have a list and links on a post I wrote about the May 2012 solar eclipse. Basically, filtered glasses specifically designed for eclipses are good (not just sunglasses, and don’t look through exposed film or mylar or anything like that unless again it’s specifically designed for looking at the Sun). You can use binoculars or a telescope to project the light from the Sun onto a piece of paper (though you can damage your optics that way). You can build a pinhole projector, but unlike an eclipse the shadow of Venus is small and may be hard to see that way. A flat mirror covered with foil can be used to project the Sun as well — this video shows you how. Again though the image may not be sharp enough to let you see Venus.
The safest way, of course, is to watch it online. The view’s better, too. But still, there’s nothing like seeing it with your own eyes. Just be careful if you do.
How to watch the transit online
Below are links where you can watch the transit live online. My top suggestion is you watch our live video star party, where we’ll have experts and live views through amateur telescopes across the planet. I’ll embed the video stream on a new blog post at the date and time of the transit, or you can watch it on CosmoQuest. That will be hosted using Hangouts On Air on Google+. If you’re signed up for G+, circle Fraser Cain to be able to participate in the chat room, too.
The more live webcasts there are, the better; it’s likely to be cloudy in some spots, so you can try others to see if they have better weather. I’ll update this list as more links come in.
Gilbert observatory to be open for Sunday's eclipse
May. 18, 2012 01:34 PM
The Republic | azcentral.com
The East Valley Astronomy Club at the Gilbert Rotary Centennial Observatory at Riparian Preserve at Water Ranch will guide families in watching a partial solar eclipse expected Sunday afternoon as well as a rare movement of Venus in front of the sun on June 5.
SNIP
VENUS TRANSIT
Venus will only block out about 3 percent of the sun June 5, she said, but with solar filters on the telescopes, viewers can see a phenomenon that won't be repeated until 2117. It will begin about 3 p.m., and viewing will take place with the powerful observatory telescope during the first three hours, as well as with individual telescopes for the length of the event through 7:30 p.m.
ABOUT
The observatory is open sunset to 9:30 p.m. every Friday and Saturday, weather permitting, at 2757 E. Guadalupe Road, Gilbert. Admission: Suggested donation of $3 per person or $5 per family. Visitors younger than high school age need to be accompanied by a parent. Information: 480-797-2019 or riparianinstitute.org.
Venus Transit and Star Party
Paradise Valley Community College at Black Mountain
34250 N. 60th St. Scottsdale, AZ, 85266
PHONE: 602-561-5398
June 5, 2012
Tuesday, 3:00 PM - 10:00 PM
ON THE WEB: here
PRICE: Free
The Phoenix Astronomical Society invites the public to watch the Venus Transit, a rare planetary alignment where Venus passes between the Sun and Earth as a small black disk which moves across the face of the Sun until sunset. Mercury, Moon, Mars and Saturn can also be viewed. Call or e-mail events@pasaz.org before 3 p.m. the day of the event to reserve a seat. Rain and wind cancels.
Eclipse expected to be most striking in decades
by Anne Ryman - May. 20, 2012 12:00 AM
The Republic | azcentral.com
SNIP
On June 5, the shadow of Venus will pass in front of the sun, a rare event that last occurred in 2004 and won't happen again until 2117.
Transit of Venus 2012: How to view once-in-a-lifetime phenomenon
June 4, 2012 | 6:35 am
The rare Transit of Venus is coming Tuesday afternoon in the United States, and it's a once-in-a-lifetime viewing chance for West Coast viewers. The next time this astronomical phenomena will happen is 2117.
Transit of Venus
At its heart, the exquisite show in the heavens is simple — Venus will cross paths between the sun and the Earth, and Earthlings will see a tiny dot floating across the surface of the sun over several hours.
How to view the Transit of Venus? You could buy a pair of solar glasses from a planetarium, like the Griffith Observatory in Los Angeles, which will sell them Tuesday after 12 p.m. for $2.99 a pair. An even better view, also at the Observatory, is seeing the transit magnified by a telescope, equipped with special solar filters.
You can also try buying No. 14 welder's glass from a welder's shop or home improvement store. Or use a pair of binoculars, preferably with more than seven times magnification, to project the sun's light onto the sidewalk or a piece of paper. If you're able to find an image of the sun, look for a tiny dot showing the image of Venus.
Transit of Venus from Los Angeles.Don't look at the sun directly. The sun's rays are so bright it will obscure Venus, and you could damage your vision. If all else fails, watch a live NASA webcast from Hawaii.
This week's viewing will be only the eighth time the Transit of Venus has happened since the telescope was invented, according to NASA's Fred Espenak. It will begin at 3:06 p.m. Pacific Daylight Time, and hit the center of its journey at 6:25 p.m. The sun sets in Los Angeles at 8:02 p.m., but in points west — such as Alaska, Hawaii, Australia, eastern Asia, and most of Europe — the show will go on for two more hours. (The transit will occur on Wednesday for points west of the International Date Line.)
As long as clouds don't interfere with the view, most of the world will be able to see at least part of the Transit of Venus, except for southeastern South America, western Africa, Portugal and Spain.
Entire lifetimes can go by with no one being able to see a Transit of Venus, but we're living in a lucky time to see what Espenak calls one of the rarest of planetary alignments. The viewings occur only twice every 120 years. Since the telescope's invention, Espenak says, it was only viewable in 1631, 1639, 1761, 1769, 1874 and 1882; the last viewable transit happened in 2004 but happened before sunrise in the western United States.
Some viewers have said the Transit of Venus looks as if there were a black hole punched in the sun, according to a NASA video.
The Transit of Venus has tantalized astronomers for centuries, and astronomers hoped that they could use the phenomenon to answer an enduring mystery — the distance between the Earth and Venus.
According to NASA, in the 18th century, astronomer Edmund Halley — whose name graces Halley’s Comet — theorized that if the Transit of Venus was observed from various locations on Earth, scientists could use that data to calculate the Earth’s distance to Venus.
European nations sent scientists on ships across the globe to observe the transit in 1769 in hopes of getting the data they needed. The British explorer James Cook was even dispatched to Tahiti to view Venus' journey. But according to a NASA video, “bad weather, primitive optics and the natural fuzziness of Venus’ atmosphere prevented observers from gathering the data they needed.” According to this NASA article, it would take another century — when observers used photographs — for scientists to get the data to measure the size of the solar system.