annular Archives

October 27, 2014December 23, 2015 by Jason Major

Orbiting Solar Observatory Sees It Burn, Burn, Burn: The Ring of Fire

Image of the Oct. 23, 2014 eclipse acquired with the Hinode spacecraft's X-ray telescope. (NASA/JAXA/SAO)

Did you catch the solar eclipse on October 23? If so, you saw the Moon “take a bite” out of the Sun (to various extents, depending on your location) during what was a partial eclipse for viewers on Earth. But for the Hinode (pronunciation alert: that’s “HEE-no-day”) solar observatory satellite, in its Sun-synchronous orbit around Earth at an altitude of 600 km (373 miles), the eclipse was annular – a “ring of fire.”

The image above was captured with Hinode’s X-ray Telescope at the moment of maximum annularity. Want to watch it burn, burn, burn like Hinode did? Check out a video below:

Not to be confused with “annual,” meaning yearly, an annular eclipse occurs when the Moon passes directly in front of the Sun but at such a distance from Earth to not quite manage to fully cover the Sun’s disk. The bright ring of visible Sun around the Moon’s silhouette gives the event its name: annular is from the Latin word anulus, meaning ring.

The next annular eclipse to be visible from Earth will occur on Sept. 1, 2016.

Led by the Japan Aerospace Exploration Agency (JAXA), the Hinode mission is a collaboration between the space agencies of Japan, the United States, the United Kingdom, and Europe, and is now in its eighth year. NASA helped in the development, funding, and assembly of the spacecraft’s three science instruments. Learn more about the mission here.

Image and video credits: NASA/JAXA/SAO

May 25, 2012December 23, 2015 by Jason Major

In the Shadow of the Moon: A Lunar View of an Eclipse

The LROC turns to capture the Moon's shadow during the May 20 solar eclipse [NASA/GSFC/Arizona State University].

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The May 20 annular eclipse may have been an awesome sight for skywatchers across many parts of the Earth, but it was also being viewed by a robotic explorer around the Moon!

During the event NASA’s Lunar Reconnaissance Orbiter turned its camera to look back home, acquiring several images of the Earth with the Moon’s fuzzy shadow cast onto different regions during the course of the eclipse. The image above is a 4-panel zoom into one particular NAC image showing the Moon’s shadow over the Aleutian Islands.

LRO captured a total of four narrow-angle camera (NAC) images during two of its orbits. During one orbit the Moon’s shadow was over the southern part of Japan, and during the next it had moved northeast to cover the island chain of Alaska.

According to the LROC site run by Arizona State University:

The NAC is a line scanner, meaning that it has only one row of 5064 pixels per camera. Instead of snapping a single frame, an image is built up by the motion of the spacecraft in orbit about the Moon (about 1600 meters per second). To obtain an image of the Earth the spacecraft is turned 180° to face the Earth, then the spacecraft is pitched as quickly as possible (one-tenth of a degree per second), so that the image is built up line by line.

This also explains why some of the images are “clipped” on the edges… LRO ran out of time during its lunar orbit. Still, it’s great to be able to show some photos of the eclipse from quite possibly the most distant viewer anywhere!

Black Friday’s Secret Solar Eclipse

Annular solar eclipse observed by the Hinode spacecraft on Jan. 6, 2011. Credit: Hinode/XRT

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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!

308331_10150381486791697_287487461696_8819975_1460644352_n — Visibility of Nov. 25 2011 annular eclipse. NASA GFSC

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.)

For a listing of past and future eclipses, both solar and lunar, visit Mr. Eclipse here. And you can read more about the Nov. 25 eclipse on AstroGuyz.com.