NASA has selected 32 of the best Earth images from 2013 and is asking readers to help select one winner.
Each week, through April 4, voters can choose their favourite image in a tournament that pit two different photos against each other.
The photo that gets the most votes in the match-up moves onto the next round.
You can even download a bracket to fill out online.
Check out all the candidates here, then head over to the Earth Observatory’s website to vote for your favourite photographs.
The is map estimates the average number of deaths per 1,000 square kilometers (386 square miles) per year due to air pollution. Dark brown areas have more premature deaths than light brown areas and blue areas have shown a decline in early deaths since 1850.
This map shows how much chlorophyll was in the ocean near the Aleutian Islands after a 2008 volcanic eruption, a natural fertiliser for the water. The levels rose above (green) or dipped below (brown) their normal levels due to an increase in phytoplankton -- a plant-like microorganism that can soak up carbon dioxide from the air.
In this map of temperature anomalies, reds and blues show how much warmer or cooler each region of the globe was was in 2012 compared to an averaged base period between 1951 and 1980.
The cross-section above the ground shows the level of aerosol extinction, or how much dust and debris blocked sunlight, after a meteor exploded over Chelyabinsk, Russia, in Feb. 2013.
A global satellite view of shipping pollution shows long tracks of higher nitrogen dioxide levels (distinct dark orange lines) seen along certain shipping routes.
The chlorophyll of blooming phytoplankton is detected off the coast of of Japan's Hokkaido and Honshu islands in late March 2013. Blue indicates areas with low concentrations of chlorophyll, and shades of yellow indicate high concentrations. Land is dark grey.
The strength of winds at the ocean's surface are measured during Super Typhoon Haiyan. Arrows indicate wind direction and colours indicate wind speed. Darker shades of purple indicate stronger winds and the strongest are red.
These maps model the relative amount of water stored near the surface and underground. The redder the area, the lower the water supply; the bluer areas are wetter. The top map shows moisture content in the top 0.8 inches of soil between Jan. 8 and Jan.14, 2013; the bottom map shows the amount of groundwater in aquifers.
The Nile's two main tributaries -- the White Nile and the Blue Nile -- are seen meeting in Khartoum, Sudan.
In a view of the Canary Islands, the Atlantic Ocean has a silvery colour, the result of sunlight being reflected off the water's surface.
The image above shows one of the most inaccessible sections of Tibet's Yarlung Tsangpo river, also known as the 'Everest of Rivers.'
Tiny airborne particles in ship exhaust act as 'seeds' that create long, thin clouds known as ship tracks.
A satellite image of northeastern China taken on Jan. 14, during one of the worst periods of air pollution in the nation's recent history, shows extensive haze, fog, and smog -- which appears grey or brown in the photo.
In December 2012, NASA and NOAA released the most detailed view of Earth at night, showing faint light down to the scale of something like a highway lamp or fishing boat.
On June 19, 2013, satellites captured a photo of smoke billowing from illegally-started wildfires on the Indonesian island of Sumatra.
On August 18, 2013, possibly the largest-ever eruption at Japan's Sakura-jima volcano sent ash 20,000 feet above Kagoshima Bay.
On Sept. 24, 2013, a major earthquake that shook western Pakistan and killed at least 350 people, also created a new island -- the small dot in the left semi-circle of water.
Fresh lava from Italy's Etna volcano is bright red in this image from February 2013. The snow is bright blue in this false-colour image.
Liège, the third most populous city in Belgium, is the bright spot at the center of this image, where continuous orange lines represent roadways and relatively dark areas show the Belgian countryside.
A photograph from the International Space Station shows the eastern half of South Georgia Island in the Atlantic Ocean.
Astronauts aboard the International Space Station snapped this striking view of Alaska's Pav lof Volcano on May 18, 2013.
Astronaut Karen Nyberg took this photograph on Aug. 5, 2013, while looking west across the Timor Sea, located north of Australia, from the International Space Station.
Astronauts on the International Space Station took this image of a plume wafting from a wildfire burning in southwestern Colorado in July 2013.
Kliuchevskoi, one of the many active volcanoes on the Kamchatka Peninsula in Russia, is seen erupting in this image from November 2013.
The island of Tristan da Cunha, located in the southern Atlantic Ocean more than 2,300 miles from the coastline of Antarctica.
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