Category: Earth

In December of 1968, the Apollo 8 capsule had successfully gone into orbit around the moon and the crew was busy taking pictures of the lunar surface. On the fourth orbit, as the Apollo spacecraft was coming around from behind the Moon, the crew saw a breathtaking sight: the Earth rising over the stark lunar horizon. Lunar module pilot Bill Anders looked up up and called out, “Wow! Look at that!”  Commander Frank Borman had a camera with black and white film, and he actually took the first picture of Earth rising over the moon. But Bill Anders managed to get some color film in his camera, and he took the color photo that’s become an icon, known simply as “Earthrise.”

On Earth Day, Bill Anders reflected on the famous picture that’s become one of the most frequently used images ever. Anders said even though it wasn’t in the original flight plan to take pictures of Earth, it didn’t take much time for him to realize how striking this view of the Earth was, and quickly snapped the celebrated image.

“I instantly thought it was ironic; we had come all this way to study the moon, and yet it was this view of the Earth that was one of the most important events for Apollo,” said Anders in an interview on NASA TV.

“There are basically two messages that came to me,” Anders said of the picture. “One of them is that the planet is quite fragile. It reminded me of a Christmas tree ornament. But the other message to me, and I don’t think this one has really sunk in yet, is that the Earth is really small. We’re not the center of the universe; we’re way out in left field on a tiny dust mote, but it is our home and we need to take care of it.”

Anders said it didn’t take long after the crew had returned home for this photograph to become iconic for the environmental movement.

“Back in the 60’s, it gave us a sense that the world was a place we all shared together,” Anders said. “We couldn’t see any boundaries from space.”

In addition to the important pictures of Earth, the Apollo 8 crew also photographed many smaller lunar features, that were previously undiscovered. Those features are located principally on the farside of the Moon in areas that had been photographed only at much greater distances by early robotic spacecraft. The Apollo 8 mission yielded more than 150 photographs of the Earth and more than 700 photographs of the Moon.

Original News Source: NASA TV

If anyone is denial about climate change possibly occuring on Earth, please take a look at this. This animation highlights the rapid loss of ice recently on the Wilkins Ice Shelf in Antarctica. Between February 28 and 29, 2008 an area of about 400 sq km disintegrated into large and small icebergs within 24 hours. As a result of the recent collapse, the remaining shelf, which totals about 14 500 sq km, is now only supported by a 6 km strip of ice. This strip is already rifted, and the remaining strip is in danger of breaking up as well.

The Wilkins Ice Shelf is a broad plate of floating ice south of South America on the Antarctic Peninsula. Since the ice shelf is already floating, this event will not cause a rise in sea level. However, ice shelves on the Antarctic Peninsula are sandwiched by extraordinarily raising surface air temperatures and a warming ocean, making them important indicators for on-going climate change.

Thousands of years of accumulated and compacted snow on the Antarctic central plateau have formed a mighty ice sheet which flows under gravity towards the coastal plane. Along the coast the ice gradually floats on the sea – to form massive ledges known as ice shelves. But as the temperature has increased, several ice shelves have broken up and disintegrated.

The images used for this annimation were taken by the ESA’s Envisat satellite. Within days of its launch, Envisat captured the disintegration of the Larsen-B ice shelf in Antarctica on 18 March 2002. Scientists estimate Larsen-B had been stable since the last ice age 12,000 years ago.

These images were acquired as part of ESA’s support to the International Polar Year (IPY) 2007-2008, a large worldwide science programme focused on the Arctic and Antarctic.

Original News Source: ESA Press Release

The traditional view of the Earth’s interior has the crust (where we live), the upper and inner mantle, the outer core, and the inner core; wrapped around each other like layers of an onion. But now textbooks will need to be revised. It turns out there’s an inner, inner core.

The core of Earth is known to have an inner core of solid iron about 2,400 km (1,500 miles). Wrapped around that is a fluid outer core that reaches 7,000 km across (4,300 miles). As the solid core rotates inside the fluid core, it generates the magnetic field that helps us navigate, and protects the planet from harmful radiation and the effects of the solar wind.

Geologists from the University of Illinois at Urbana-Chamaign have been probing the interior of the planet, trying to get a better sense of its structure. And that’s harder than it sounds. You can’t just look down through thousands of km of solid rock.

There were using the natural waves that pass through the Earth after earthquakes shake on the surface. The waves are bent and reflected as they pass through the various layers inside the planet.

The team was specifically studying how the waves were affected as they passed through the solid inner core and were surprised to see that it wasn’t a uniform sphere of iron.

Instead, the seismic waves clearly showed that there’s an additional layer at a diameter of 1,180 km (733 miles), which makes this less than half the diameter of the inner core.

This is the Earth’s inner, inner core.

So what is it? Here’s what the lead scientists, Xiaodong Song had to say:

“Our results suggest the outer inner core is composed of iron crystals of a single phase with different degrees of preferred alignment along Earth’s spin axis,” Sun said. “The inner inner core may be composed of a different phase of crystalline iron or have a different pattern of alignment.”

It’s still iron, just not in the same crystalline structure. Perhaps its time to give the layers new names, inner inner core doesn’t quite work for me.

Original Source: University of Illinois News Release

This picture was released a couple of days ago, but since it’s so special, it deserves a post on Universe Today. And besides, everyone secretly likes to look at pictures of themselves. And this is a picture of us: it’s the Earth and the moon, as seen from Mars. From the Mars Reconnaissance Orbiter, to be exact, and it was taken by the HiRISE Instrument on board, the High Resolution Imaging Science Experiment. That’s the same camera that gave us the images of the avalanche on Mars, so the capabilities of this instrument are quite spectacular. This image was snapped back in October 2007, from a distance of 142 million kilometers, and if you look closely, you can make out a few features on Earth.

The west coast outline of South America is at lower right on Earth, although the clouds are the dominant features. In fact, the clouds were so bright, compared with the Moon, that they almost completely saturated the filters on the HiRISE camera. The people working on HiRISE say this image required a fair amount of processing to make a such a nice-looking picture. Yes, I agree, we are looking quite nice.

The phase angle is 98 degrees, which means that less than half of the disks of the Earth and Moon have direct illumination from the sun; that’s the reason we only see about half of each object. The scientists working on HiRISE say they would be able to image the Earth and moon when they are fully illuminated, but only when they are on the opposite side of the sun from Mars. However, then the distance would be much greater and the image would show less detail.

At this distance, this HiRISE image has a scale of 142 km/pixel, giving the Earth diameter about 90 pixels and the Moon diameter 24 pixels.

And now, back to the target that HiRISE was originally designed for: Mars. Here’s a very colorful (and false color) image that highlights the different minerals in Nili Fossae on Mars, one of the potential landing sites for the Mars Science Laboratory rover. From the CRISM instrument, the on-board spectrometer, scientists can discern that this area on Mars contains iron and magnesium, minerals that also contain water.

Original News Source: HiRISE Web page