A video posted today by the team at NASA’s Solar Dynamics Observatory shows two recent events on the Sun: a twisting prominence and the “eclipse” of a plasma eruption by the structure of a darker, cooler filament. Most impressive!
From the SDO team:
Over the past 24 hours we have seen some beautiful solar events. None of them have a direct impact on Earth, but they are astonishing to watch. It just shows how an active star our Sun really is… far from boring!
On December 8, 2011 a twisting prominence eruption occurred on the lower eastern limb. The view through the AIA 304 angstrom filter shows us this beautiful eruption.
In the early hours of December 9, 2011 SDO observed a little bit of a different eclipse. An erupting cloud of plasma was eclipsed by a dark magnetic filament. The eruption is still on the far side of the Sun, behind the eastern limb and is slowly moving forward and over the limb sometime next week.
In front you can observe the filament of relatively cool dark material floating across the Sun’s surface in the foreground. That filament partially blocks the view of the hot plasma eruption behind it.
Excellent footage of our constantly-active Sun! It’s easy to forget too that these events and structures are many, many times larger than our entire planet… the sheer power of a star is quite an impressive thing to see. Thanks to SDO we get an unblinking front-row seat to all the action!
While many in the U.S. will be recovering from Thanksgiving day meals and looking for ways to stretch their holiday shopping dollars at (hopefully local) retailers’ “Black Friday” sales, the face of the Sun will grow dark as the Moon passes in front of it, casting its shadow over the Earth. But it won’t be visible to American shoppers – or very many people at all, in fact… this eclipse will be hiding in the southern skies above Antarctica!
On Friday, November 25, an annular eclipse will occur, reaching a maximum coverage at 06:20:17 UT of magnitude .905. It will be the largest – and last – partial eclipse of the year.
But its visibility will be limited to the most southern latitudes… outside of the Antarctic continent, only New Zealand, Tasmania and parts of South Africa will have any visibility of the event.
An annular eclipse is similar to a total eclipse, except that the Moon is at a further distance from Earth in its orbit and so does not completely cover the disc of the Sun. Instead a bright ring of sunlight remains visible around the Moon’s silhouette, preventing total darkness.
The next solar eclipse will occur on May 20, 2012. It will also be annular, and even darker than the Black Friday one at a magnitude of .944. It will be visible from China, Japan, the Pacific and Western U.S.
Following that, the main event of 2012 would have to be a total eclipse on November 13, which will be visible from Australia, New Zealand and South America (greatest totality will occur over the South Pacific.) Several sites have already set up group travel events to witness it!
Feeling left out on cosmic occultations? Not to worry… there will be a very visible total lunar eclipse on the night of December 10, 2011 (weather permitting, of course) to viewers across the Northern Hemisphere. The Moon will pass into Earth’s shadow, turning gradually darker in the night sky until it is colored a deep rusty red. It’s a wonderful event to watch, even if not as grandiose as a total eclipse of the Sun.
(Plus it’s completely safe to look at, as opposed to solar eclipses which should never be directly observed without safety lenses or some projection device… for the same reasons that you shouldn’t stare at the Sun normally.)
On June 15 there will be a total lunar eclipse visible from Australia, Indonesia, southern Japan, India, a large area of Asia, Africa, Europe and the eastern part of South America. This is expected to be one of the darkest eclipses ever (with a magnitude of 1.7), second only to the July 2000 eclipse.
Sadly it won’t be visible to viewers in North America, but much of the rest of the world should be treated to a wonderful show as the Moon slips into Earth’s shadow. Gradually growing darker from its western limb inwards, the Moon then gains a bluish cast which transitions to orange then deep red as it moves into light passing through the edge of Earth’s atmosphere (the same as what makes the colors of a sunset) and then eventually going almost completely dark before the process then reverses itself from the opposite side.
The entire eclipse will last 5 hours and 39 minutes, with a totality duration of 1 hour and 40 minutes. It will begin at 17:23 UT.
Viewers in Australia and eastern Asia will see the eclipse begin as the Moon is setting while those in Europe and South America will see it as the Moon is rising. Only locations in India, eastern Africa, the Middle East and western Asia will experience the entire eclipse.
This is the first of two total lunar eclipses in 2011; the next will take place on December 10.
I saw my first total lunar eclipse last December, which took place on the night of the winter solstice (December 21). It really was an amazing event to watch… in totality the Moon was colored a deep coppery red and really just seemed to be suspended among the stars – it felt like you could just reach up and pluck it from the sky! If you are in any of the areas where this next one is visible I encourage you to check it out for yourself!
Although the word “transit” can have many meanings, here on Universe Today, we’re talking about astronomical transits. This is where one object in space moves directly in front of another, partly obscuring it from view.
The most famous example of an astronomical transit is a solar eclipse. From our vantage point on Earth, the Moon appears to pass directly in front of the Sun, obscuring it, and darkening the sky. When seen from space, the Moon casts a shadow on the surface of the Earth; only people within that shadowed area actually see the transit.
In order to have a transit, you need to have a closer object, a more distant object, and then an observer. When all three objects are lined up in a straight line, you’ll get a transit. There can be transits of Mercury and Venus across the surface of the Sun, or a transit of Earth across the Sun, seen from Jupiter. We can also see the transit of moons across the surface of their planets. Jupiter often has moons transiting in front of it.
Astronomers use the transit technique to discover extrasolar planets orbiting other stars. When a planet passes in front of a star, it dims the light from the star slightly. And then the star brightens again as the planet moves away. By carefully measuring the brightness of the star, astronomers are able to detect if they have planets orbiting them.
Transits are also helpful for studying the atmospheres of objects in the Solar System. Astronomers discovered that Pluto has a tenuous atmosphere by studying how it dimmed the light from a more distant star. As Pluto began transiting in front of the star, its atmosphere partly obscured the star, changing the amount of light observed. Astronomers were then able to work out the chemicals in Pluto’s atmosphere.
The next transit of Mercury will occur in 2016, and the next transit of Venus is scheduled to occur in 2012.
We have written many articles about astronomical transit for Universe Today. Here’s an article about the transit of Mercury, and here’s an article about the transit of Venus.
On July 11, 2010, the new moon passed directly in front of the sun, causing a total solar eclipse. The path of totality stretched across the South Pacific Ocean, and the Moon’s umbral shadow didn’t make landfall except for a few spots; Mangaia (Cook Islands) and Easter Island (Isla de Pascua), southern Chile and Argentina, with a partial eclipse visible from a much larger region covering the South Pacific and southern South America. On hand to witness the event at Easter Island were Jonathan and Michael Doochin, who graciously shared several of the images included here. You can also check out Jonathan’s Twitpic page for more pictures of the eclipse as seen on Easter Island.
In this image, the solar eclipse is shown in gray and white from a photo provided by the Williams College Expedition to Easter Island and was embedded with an image of the sun’s outer corona taken by the Large Angle Spectrometric Coronagraph (LASCO) on the SOHO spacecraft and shown in red false color. LASCO uses a disk to blot out the bright sun and the inner corona so that the faint outer corona can be monitored and studied. Further, the dark silhouette of the moon was covered with an image of the sun taken in extreme ultraviolet light at about the same time by the Atmospheric Imaging Assembly on the Solar Dynamics Observatory. The composite brings out the correlation of structures in the inner and outer corona.
Here you can see multiple eclipses; the team from Williams College used a cheese grater as a pinhole camera to view the eclipse.
What an amazing sight this must have been — a rainbow formed in the skies over Easter Island as people were setting up their cameras for the eclipse event.
The recently launched Proba-2 satellite was able to observe the annular solar eclipse on January 15, 2010, with stunning results. The PRoject for OnBoard Autonomy satellite was launched on November 2, 2009 and is intended to test hardware and software that might be incorporated into future ESA missions. The eclipse offered a unique chance to test out the Sun-imaging instrument, SWAP (Sun Watcher using APS detectors and imaging processing). Another radiometer instrument was also able to take measurements during the eclipse.
Proba-2 is one of the smallest satellites launched. The 0.6m by 0.6m by 0.8m satellite contains several instruments, a computer, battery, thrusters, and solar panel systems.
The eclipse was also detected by the Proba-2’s LYRA (Lyman Alpha Radiometer) instrument, the first ultraviolet radiometer in space that employs diamond detectors. LYRA will measure solar flares with an unprecedented rapid time resolution of 0.5 sec. LYRA data will soon be feeding research investigations and space weather forecasts.
Proba-2 was a secondary payload included on the launch of the SMOS mission, the Soil Moisture and Ocean Salinity Earth Explorer.
The Cassini mission is just a non-stop faucet of fantastic images! Here are two that were released today, for your viewing pleasure. The first image, above, is an eclipse of Saturn’s moon Tethys, which lies in the background, by Dione. The three images were each taken one minute apart.
As you can see, from Cassini’s perspective Dione passes right in front of Tethys. Make no mistake in thinking that these two Saturnian companions are close together in this shot, however; Dione, the moon in the foreground, is 2.2 million kilometers (1.4 million miles) from the Cassini spacecraft, while Tethys is 2.6 million kilometers (1.6 million miles) away.
An interesting feature of the image is how Tethys appears brighter on the side of the moon opposite the Sun. This is because Saturn, which lies out of the image to the right, is reflecting light from the Sun back onto the moon. Dione is not being backlit by Saturn from the vantage point of Cassini, so its face that is opposite the Sun appears darker.
Visible on Tethys is the Odysseus Crater, which spans a whopping 400km (240 miles). Given that Tethys is only 1,062 kilometers, or 660 miles across, the crater appears very large in comparison to the moon. It also makes the moon very much resemble the Death Star from Star Wars, don’t you think? These images were taken using Cassini’s narrow-angle camera on Nov. 28, 2009.
This second image is a synthetic aperture radar image of the surface of Saturn’s moon Titan. In the lower right and upper center of the image, the two wrinkly features are actually small Titanian mountains. What exactly causes the grooves in these mountains has still to be determined.
On Earth, the shifting of tectonic plates can form such structures, as well as the processes of water flowing, freezing, and melting.
Since Titan has an atmosphere composed mostly of methane and ethane, and experiences rain much like here on Earth, it’s quite possible that these processes are the cause of such features.
Because the illumination of this image comes from the radar on Cassini, the peaks of these formations should be the brightest. As is visible, this isn’t the case. Notice how the left side of the upper mountain in the image, and right side of the lower-right mountain are brighter. The materials that make up the darker and lighter areas are the cause for this lighting effect.
The image represents a patch of Titan’s surface 250 km (155 miles) high and 285 km (180 miles) wide, and the resolution is about 350 meters (1,150 feet) per pixel, and it was taken on December 28th, 2009.
The first of two solar eclipses to occur in 2010 took place Friday, January 15. This was an annular eclipse, which means the Sun was not totally covered by the Moon, creating a “ring of fire.” The eclipse was visible from a 300-km-wide track that passed over central Africa, across the Indian Ocean, over the southern tip of India and the northern end of Sri Lanka, and then across parts of Bangladesh and Myanmar. At the center of the track, the eclipse endured for 11 minutes and eight seconds, setting a record that won’t be beaten until December 23, 3043. Weather cooperated in many regions, allowing good viewing conditions. Here are a few images and videos from Daniel Fischer, who was in Varkala, India, and another group who calls themselves Eclipse Hunt 2010 crew were in Jaffna, Sri Lanka. The image above is from Fischer, who said via Twitter that his travels to view the eclipse was a total success. “Deep blue sky, not a single cloud all day, photo plans worked.”
This image is from the Eclipse Hunt 2010 crew, in northern Sri Lanka. It was taken by Shehal Joseph and Romayne Anthony. They used a Celestron NexStar 5se telescope with a focal length of 1.25m, and an energy rejection filter.
Why the “ring of fire?” During an annular eclipse, the moon is a little further than average away from the earth and its angular size in the sky is therefore slightly smaller than the angular size of the sun. So it is like the Moon is silhouetted against the Sun, and it doesn’t cover the Sun entirely. A a ring, or annulus, of sunlight can be seen around the black disk of the moon.
NASA’s Aqua satellite was looking down from space at 1:15 p.m. Calcutta time (7:45 UTC) on January 15, 2010, and saw the Moon’s shadow cast on Earth. The Moderate Resolution Imaging Spectroradiometer (MODIS) on Aqua images this shadowed area in India and the Bay of Bengal. The shadow spanned a north-south distance of about 300 kilometers (185 miles) on the surface, with the darkest part near the mid-point of the span.
This is another image from the Fischer’s group of astrophotographers in India. By taking a long-exposure image, the sun’s chromosphere was able to be seen.
Normally with an annular eclipse, not a lot of science is able to be done, said Jay Pasachoff, who leads the IAU’s working group on eclipses. “Because it doesn’t get completely dark, we won’t be able to see the solar corona, the diamond ring, or the fantastically interesting and beautiful phenomena that one sees at a total solar eclipse, but still annular eclipses are interesting to see,” Pasachoff said on the 365 Days of Astronomy podcast. “You have to keep a solar filter on to look through for the whole time. The partial phases that last an hour and a half and the annular phase, which, for this eclipse, lasts, in many places, over ten minutes – very long for an eclipse.”
Interestingly, the images shown here by Fischer’s group used a very low-tech combination of a compact camera and their filters were two “rescue sheets,” the thin aluminum foil-like thermal blankets usually given out during emergency situations, such as the recent earthquake in Haiti.
This high-resolution image obtained using a telescope was taken by Fischer’s group in India. “The Ring of Fire is closed, but just barely; it measures a few arc seconds only in places in this super-sharp telescopic image,” said Fischer, via Twitter.
The next solar eclipse will be a total eclipse, on July 11th, 2010. “That won’t be seen by very many people at all,” said Pasachoff. “It is largely over the Pacific Ocean, where it will cross some normally uninhabited atolls not far from Tahiti, so there’ll be some ships there and some few expeditions out of Tahiti to see that. The major land in the way is a very unusual island, Easter Island. It’s in the middle of the Pacific, some 4,000 miles west of the coast of Chile.”
Plane of the ecliptic, also known as the ecliptic plane, is a phrase you will often hear in astronomy. A basic definition is that the plane of the ecliptic is the plane of the Earth’s orbit, but that does not mean much to most people. Space is a three-dimensional vacuum, which you can think of as a kind of pool with the planets suspended in it. The Earth orbits the Sun on a particular angle and its orbit is elliptical in shape. The orbit is often shown as an ellipse made of dotted lines with the Sun at its center. If you made this ellipse a solid surface and extended it infinitively, then you would have the plane of the ecliptic. Actually our entire Solar System can be thought of as flat because all of the planets’ orbits are near or on this plane.
The ecliptic plane is used as the main reference when describing the position of other celestial objects in our Solar System. The angle between the plane of the ecliptic and the plane of an orbit is called the inclination. Until it was stripped of its status as a planet, Pluto was the planet with the most extreme inclination – 17°. Mercury is the only other planet with a significant inclination of 7°. There is also a 7° inclination between the plane of the Sun’s equator and the ecliptic plane. There are other celestial bodies that have a much greater inclination than any of the planets, such as Eris with a 44° inclination or Pallas with a 34° inclination.
The ecliptic plane got its name from the fact that a solar eclipse can only happen when the Moon crosses this plane to block out the Sun. Our Moon crosses the ecliptic about twice a month. A solar eclipse occurs when a new Moon crosses the ecliptic, and a lunar eclipse occurs when a full Moon crosses it.
Seasons on Earth are caused by our planet’s axial tilt of 23.5°, which causes variations in the amount of sunlight different parts of the Earth receive. This goes for all the other planets too. For example, Uranus rotates on its side with an axial tilt of 97.8°, which results in extreme variations in its seasons. The eclipse is also home to the constellations of the zodiac. There are twelve constellations in the zodiac, which are important symbols in astrology and can also be found in the Chinese calendar. Here’s a list of all the zodiac symbols.