Sunscreen in the Sky? Reflective Particles May Combat Warming
In the image: Titanium dioxide, as seen through a scanning electron microscope.
Titanium dioxide could scatter sunlight and cool Earth, scientist says.
Spritzing a sunscreen ingredient into the stratosphere could help counteract the effects of global warming, according to scientists behind an ambitious new geoengineering project.
The plan involves using high-altitude balloons to disperse millions of tons of titanium dioxide—a nontoxic chemical found in sunscreen as well as in paints, inks, and even food.
Once in the atmosphere, the particles would spread around the planet and reflect some of the sun’s rays back into space.
About three million tons of titanium dioxide—spread into a layer around a millionth of a millimeter thick—would be enough to offset the warming effects caused by a doubling of today’s atmospheric carbon dioxide levels, according to project leader and chemical engineer Peter Davidson.
10 interesting facts about planet Earth
1. Plate tectonics keep the planet comfortable
Earth is the only planet in the Solar System with plate tectonics. The outer crust of the Earth is broken up into regions known as tectonic plates. These are floating on top of the magma interior of the Earth and can move against one another. When two plates collide, one plate can go underneath another.
This process is very important. When microscopic plants in the ocean die, they fall to the bottom of the ocean. Over long periods of time, the remnants of this life, rich in carbon, are carried back into the interior of the Earth and recycled. This pulls carbon out of the atmosphere, which makes sure we don’t get a runaway greenhouse effect, like what happened on Venus.
Without the plate tectonics, there’d be no way to recycle this carbon, and the Earth would overheat.
2. Earth is almost a sphere
The Earth’s shape could be described as an oblate spheroid. It’s kind of like a sphere, but the Earth’s rotation causes the equator to bulge out . What this means is that the measurement from pole to pole is about 43 km less than the diameter of Earth across the equator.
Even though the tallest mountain on Earth is Mount Everest, the feature that’s furthest from the center of the Earth is actually Mount Chimborazo in Ecuador.
3. Earth is mostly iron, oxygen and silicon
If you could separate the Earth out into piles of material, you’d get 32.1 % iron, 30.1% oxygen, 15.1% silicon, and 13.9% magnesium. Of course, most of this iron is actually down at the core of the Earth. If you could actually get down and sample the core, it would be 88% iron. 47% of the Earth’s crust consists of oxygen.
4. 70% of the Earth’s surface is covered in water
When astronauts first went into the space, they looked back at the Earth with human eyes for the first time, and called our home the Blue Planet. And it’s no surprise. 70% of our planet is covered with oceans. The remaining 30% is the solid ground, rising above sea level.
5. The Earth’s atmosphere extends out to 10,000 km
The atmosphere is thickest within the first 50 km or so, but it actually reaches out to about 10,000 km above the surface of the planet. This outermost layer of the atmosphere is called the exosphere, and starts about 500 km above the surface of the Earth. As we said, it goes all the way up to 10,000 km above the surface. At this point, free-moving particles can actually escape the pull of Earth’s gravity, and be blown away by the Sun’s solar wind.
But this high atmosphere is extremely thin. The bulk of the Earth’s atmosphere is down near the Earth itself. In fact, 75% of the Earth’s atmosphere is contained within the first 11 km above the planet’s surface.
Want more planet Earth facts? We’re halfway through. Here come 5 more.
6. The Earth’s molten iron core creates a magnetic field
The Earth is like a great big magnet, with poles at the top and bottom of the planet, near to the actual geographic poles. This magnetic field extends from the surface of the Earth out thousands of kilometers – a region called the magnetosphere.
Be grateful for the magnetosphere. Without it particles from the Sun’s solar wind would hit the Earth directly, exposing the surface of the planet to significant amounts of radiation. Instead, the magnetosphere channels the solar wind around the Earth, protecting us from harm.
Scientists think that the magnetic field is generated by the molten outer core of the Earth, where heat creates convection motions of conducting materials. This generates electric currents that create the magnetic field.
7. Earth doesn’t take 24 hours to rotate on its axis
It’s actually 23 hours, 56 minutes and 4 seconds. This is the amount of time it takes for the Earth to completely rotate around its axis; astronomers call this a sidereal day. Now wait a second, that means a day is 4 minutes shorter than we think it is. You’d think that time would add up, day by day, and within a few months, day would be night, and night would be day.
Remember that the Earth orbits around the Sun. Every day, the Sun moves compared to the background stars by about 1° – about the size of the Moon in the sky. And so, if you add up that little motion from the Sun that we see because the Earth is orbiting around it, as well as the rotation on its axis, you get a total of 24 hours. Now that sounds like the day we know.
8. A year on Earth isn’t 365 days
It’s actually 365.2564 days. It’s this extra .2564 days that creates the need for leap years. That’s why we tack on an extra day in February every year divisible by 4 – 2004, 2008, etc – unless it’s divisible by 100 (1900, 2100, etc)… unless it’s divisible by 400 (1600, 2000, etc).
9. Earth has 1 moon and 2 co-orbital satellites
As you’re probably aware, Earth has 1 moon (The Moon). But did you know there are 2 additional asteroids locked into a co-orbital orbits with Earth? They’re called 3753 Cruithne and 2002 AA29. We won’t go into too much detail about the Moon, I’m sure you’ve heard all about it.
3753 Cruithne is 5 km across, and sometimes called Earth’s second moon. It doesn’t actually orbit the Earth, but has a synchronized orbit with our home planet. It has an orbit that makes it look like it’s following the Earth in orbit, but it’s actually following its own, distinct path around the Sun.
2002 AA29 is only 60 meters across, and makes a horseshoe orbit around the Earth that brings it close to the planet every 95 years. In about 600 years, it will appear to circle Earth in a quasi-satellite orbit. Scientists have suggested that it might make a good target for a space exploration mission.
10. Earth is the only planet known to have life
We’ve discovered past evidence of water on Mars, and the building blocks of life on Saturn’s moon Titan. We can see amino acids in nebulae in deep space. But Earth is the only place life has actually been discovered.
But if there’s life on other planets, scientists are building the experiments that will help find it. A new rover called the Mars Science Laboratory will be heading to Mars in the next few years, equipped with experiments that can detect life in the soil on the Red Planet. Giant radio dishes scan distant stars, listening for the characteristic signals of intelligent life reaching out across interstellar space. And new space telescopes, such as the European Space Agency’s Darwin mission might be powerful enough to sense the presence of life on other worlds.
Following a Moon Shadow
Image courtesy PHL/UPR Arecibo
Seen from one of Japan’s MTSAT meteorological satellites, the shadow of the moon darkens part of the North Pacific during the annular solar eclipse last Sunday and Monday. Despite the diminutive shadow shown, the moon is actually a little bigger than a quarter the size of Earth.
An annular eclipse happens when the moon lines up between Earth and thesun, and when the dark moon’s apparent diameter is smaller than the visible disk of the sun, leaving a ring—or annulus—of fiery light around the edges.
(See more 2012 annular solar eclipse pictures.)
Earth from Space
1. Desert’s End
Photograph courtesy NASA via NASA Earth Observatory
In Eastern Algeria’s stretch of the Sahara, the Tifernine Dune Field - a section of the Grand Erg Oriental dune sea - meets the Tinrhert Plateau, as seen in a 2008 astronaut photograph.
2. Sea Snakes
Photograph courtesy CNES/Spot Image/ESA
Gullies slithering through sandbanks are seen in the Wadden Sea, near the Netherlands, in a 2006 satellite image.
3. Circulation System
Photograph courtesy NASA and NASA Earth Observatory
Tidal flats and channels on the western side of the Bahamas’ Long Island are seen in a 2010 astronaut photograph.
4. Circles of Life
Photograph courtesy NASA and NASA Earth Observatory
Fields near the city of Perdizes, in the Minas Gerais state of Brazil, are seen in a 2011 astronaut photograph.
Iconic Images of Earth from Space
Blue Marble: NASA has produced several Blue Marble images. The original, taken by the crew of Apollo 17, shows the Eastern Hemisphere and is thought to be one of the most famous and widely distributed images of Earth ever. Above-left, one of the most recent Blue Marble images was created by stitching together satellite imagery and reveals the Western Hemisphere in all its glory. The first pictures from space were not nearly as routine as the Blue Marbles are now.
1. A “Blue Marble” image of the Earth taken from the VIIRS instrument aboard NASA’s most recently launched Earth-observing satellite, Suomi NPP. This composite image uses a number of swaths of the Earth’s surface taken on Jan. 4, 2012.
First Picture of Earth and Moon in Single Frame: It was incredible to see Earth from deep space for the first time. It was yet another amazing experience to see both our world and its moon suspended in the black void together for the first time. That feat was accomplished by Voyager 1 on its way to the outer planets.
2. This NASA picture of the Earth and the moon in a single frame, the first of its kind ever taken by a spacecraft, was recorded Sept. 18, 1977, by Voyager 1 when it was 7.25 million miles (11.66 million kilometers) from Earth. The moon (top) is beyond the Earth as viewed by the space probe. Because the Earth much brighter than the moon, the moon was artificially brightened by a factor of three by computer enhancement so that both bodies would show clearly in the image.
Earthrise: Imagine coming around the moon in a spaceship, looking out the window, and being the first humans to see your own planet rise. This iconic image of the Earth rising, popularly called the “Earthrise” picture, is the first of its kind taken by an astronaut from lunar orbit.
3. This view of the rising Earth greeted the Apollo 8 astronauts as they came from behind the moon after the lunar orbit insertion burn. The photo is displayed here in its original orientation, though it is more commonly viewed with the lunar surface at the bottom of the photo. Earth is about five degrees left of the horizon in the photo. The unnamed surface features on the left are near the eastern limb of the moon as viewed from Earth. The lunar horizon is approximately 780 kilometers from the spacecraft. The height of the photographed area at the lunar horizon is about 175 kilometers.
Moonrise from Earth Orbit: The horizon is tilted and seems far away. The moon appears to float on Earth’s atmosphere. It’s one of many incredible views that can come only from space, yet by name it’s totally familiar: a moonrise.
4. A quarter moon rises above Earth’s horizon and above the airglow of our atmosphere. The image was made with a digital still camera on the final mission of the Space Shuttle Columbia. Columbia’s crew was killed on Feb. 1, 2003, when the shuttle broke up on re-entry into Earth’s atmosphere.
(Source: livescience.com)
Happy Equinox
Hundreds of pictures of Earth, each taken at about 6AM , showing the terminator - the day/night line - over the course of one year (2010sep-2011sep).
Taken by METEOSAT-9 Earth-observing satellite.
Watch the Video here
Credit: NASA Earth Observatory
Gliese 581g
Gliese 581g is the first world discovered beyond Earth that’s the right size and location for life. The new world orbits right in the middle of that system’s habitable region, where temperatures would be suitable for liquid water to pool on the planet’s surface.
A Volcanic Rainbow in the Hottest Place on Earth
The Blue Marble
1. 2012. A ‘Blue Marble’ image of the Earth taken from the VIIRS instrument aboard NASA’s most recently launched Earth-observing satellite—Suomi NPP. This composite image uses a number of swaths of the Earth’s surface.
2. 2012. A view of the eastern hemisphere of earth from space. NASA’s second ‘Blue Marble’ image was created from data acquired by a new instrument aboard the Earth-observing satellite Suomi NPP, the Visible Infrared Imaging Radiometer Suite (VIIRS).
3. 1972. View of the Earth as seen by the Apollo 17 crew traveling toward the moon. This translunar coast photograph extends from the Mediterranean Sea area to the Antarctica south polar ice cap. This is the first time the Apollo trajectory made it possible to photograph the south polar ice cap. Note the heavy cloud cover in the Southern Hemisphere. Almost the entire coastline of Africa is clearly visible. The Arabian Peninsula can be seen at the northeastern edge of Africa. The large island off the coast of Africa is the Malagasy Republic. The Asian mainland is on the horizon toward the northeast.
(Source: TIME)
‘Potato’ Earth Shows How Gravity Takes Shape
Gravitational model of Earth over the Atlantic Ocean. The red color represents 100-meter-high deviations in height from an ideal geoid, where gravity is constant, and the blue areas represent 100-meter-low deviations
Celebrate Earth Day in Super High Resolution
Changing Weather
The Elektro-L 1 satellite captures the changing weather of the planet below each half hour. The top image was taken May 14, while the lower image, which shows large shifting weather patterns, was taken months later, in October.
These images may be among the largest single photos ever taken of our planet, according to James Drake, who processed them. You can download full-resolution, 11,000 x 11,000 pixel versions of the top and bottom images but, be warned, they are each larger than 100 MB.
(Source: Wired)
Equinox
Equinox means “equal night” in Latin, capturing the idea that daytime and nighttime are equal lengths everywhere on the planet. That is true of the Sun’s presence above the horizon, though it does not account for twilight, when the Sun’s rays extend from beyond the horizon to illuminate our gas-filled atmosphere.
Credit: NASA EUMETSAT; image from March 20, 2011
