Pacific Glory

An optical phenomenon known as a “glory” is seen over a cloud-covered Pacific Ocean in this image from NASA’s Aqua satellite, acquired on June 20, 2012. Although the colors may make it look like a rainbow, the process behind its formation is somewhat different.

As vortices spiral off the leeward side of Guadalupe Island, off the western coast of Baja California, a shimmering spectrum of colors highlights a glory just west of the island. Glories are created when light from the Sun reflects back toward an observer off water droplets within clouds or fog. They are often seen from airplanes as a bright ring of light encircling a silhouetted shadow of the aircraft below, but are also visible from the ground and, sometimes, even from space.

From the NASA Earth Observatory website:

Although glories may look similar to rainbows, the way light is scattered to produce them is different. Rainbows are formed by refraction and reflection; glories are formed by backward diffraction. The most vivid glories form when an observer looks down on thin clouds with droplets that are between 10 and 30 microns in diameter. The brightest and most colorful glories also form when droplets are roughly the same size.

From the ground or an airplane, glories appear as circular rings of color. The space shuttle Columbia observed a circular glory from space in 2003. In the image above, however, the glory does not appear circular. That’s because MODIS scans the Earth’s surface in swaths perpendicular to the path followed by the satellite. And since the swaths show horizontal cross sections through the rings of the glory, the glory here appears as two elongated bands of color that run parallel to the path of the satellite, rather than a full circle.

Glories always appear around the spot directly opposite the Sun, from the perspective of the viewer. This spot is called the anti-solar point. To visualize this, imagine a line connecting the Sun, a viewer, and the spot where the glory appears. In this case, the anti-solar point falls about halfway between the two colored lines of the glory.

Click here to download the full-size image.

NASA image courtesy Jeff Schmaltz, LANCE MODIS Rapid Response. Read more here.

What Is The Largest Island In The World

Greenland. Image credit: NASA

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If you were asked what is the largest island in the world, what would you say? Australia maybe? Greenland is the worlds largest island. While Australia is an island, it is considered a continent. Greenland has an area of 2,166,086 square km, but a meager population of 56,452. The populations is over 85% Inuit. The remaining inhabitants are mainly Danish. The average annual temperature of Greenland varies between -9 to 7 °C.

Greenland is an autonomous country within the Kingdom of Denmark. Greenland is a group of islands and Greenland is the name of the largest, most populated one. Greenland has been inhabited on and off since 2500 BC. Denmark established rule in the 18th century. In 1979 Denmark granted home rule, in a relationship known as the Commonwealth of the Realm and in 2008 Greenland voted to transfer more powers to the local government. The Danish royal government is only in charge of foreign affairs, security, financial policy, and providing a subsidy to each citizen.

Greenland is bordered by the Atlantic Ocean to the southeast, the Greenland Sea to the east, the Artic Ocean to the north, and Baffin Bay to the west. The nearest countries to Greenland are Iceland to the east and Canada to the west. The country also contains the world’s largest national park. Scientists have thought for decades that the ice sheet covering the country may actually conceal three separate island land masses that have been bridged by glaciers over the last geologic cooling period.

The Greenland ice sheet covers 1,755,637 square km. It has a volume of 2,850,000 cubic km. Gunnbjorn Fjeld is the highest point on Greenland at 3,700 m. The majority of Greenland is less than 1,500 m in elevation. The weight of the ice sheet has formed a basin that is more than 300 m below sea level.

Between 1989 and 1993, climate researchers drilled into the summit of Greenland’s ice sheet, obtaining a pair of 3 km ice cores. Analysis of the layering and chemical composition of the cores has provided a revolutionary new record of climate change going back about 100,000 years. It illustrated that the world’s weather and temperature have often shifted rapidly from one stable state to another. The glaciers of Greenland are also contributing to a rise in the global sea level at a faster rate than was previously believed.

Greenland is fascinating and intimidating at the same time. To live there is a daily struggle against the elements that has forged a tough people.

We have written many articles about Greenland for Universe Today. Here’s an article about the growing ice sheets in Greenland, and here are some images of Greenland from space.

If you’d like more info on Earth’s islands, check out NASA’s Solar System Exploration Guide on Earth. And here’s a link to NASA’s Earth Observatory.

We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.

Sources:
World Atlas
Geographia

Pictures of Islands

Here are some cool pictures of islands… from space!

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This is a picture of South Georgia Island, one of the southernmost islands in the world, off the tip of South America. It was used as a whaling base and now has no permanent inhabitants, other than some scientists. In this picture, taken by NASA’s Terra satellite, the entire island is covered in snow. Here are some more island pictures.


Surtsey Island
Surtsey Island

This is a picture of Surtsey Island, captured by the IKONOS satellite. This volcanic island is one of the newest in the world, breaking through the surface of the ocean in 1963. The volcanoes that formed the island erupted for about 4 years and then stopped, and now erosion from the ocean is wearing it back down again.


Ascension Island
Ascension Island

Next in our pictures of islands is Ascension Island. You can see the airstrip down on the lower right side of the island, and a cinder cone above it. The northern part of the island has lava flows and you can see individual clouds above the island. Ascension Island is one of the space shuttle’s alternative landing sites.


Palm Island
Palm Island

Here’s a picture of a completely man made island. This is Palm Island, off the coast of Dubai in the United Arab Emirates. Now complete, it has palm fronds surrounded by a circular breakwater. There will eventually be more than 100 luxury hotels, marinas, water theme parks, and many houses.


Akpatok Island
Akpatok Island

This is a picture of Akpatok Island, in Northern Quebec, which is accessible only by air. The picture was taken by a Landsat satellite.

We have written many articles about islands for Universe Today. Here’s an article about the biggest island on Earth, and here are more pictures of islands from space.

You can find many more pictures from NASA’s Earth Observatory site.

We have recorded a whole episode of Astronomy Cast just about our planet. Listen to it here, Episode 51: Earth.