As greenhouse gases cause average temperatures to climb worldwide, human health will suffer, scientists say.

A study in the journal Nature Climate Change suggests that heat deaths in Manhattan will increase over the rest of this century in connection with higher temperatures associated with global warming. In the 2020s, heat-related deaths could rise about 20% compared with the 1980s, according to the research.

"This paper helps to remind people that climate change is real, that it’s happening and we need to prepare and make ourselves as resilient as we can to climate change," said Patrick Kinney, the study's senior author and director of the Columbia Climate and Health Program at Columbia University's Mailman School of Public Health. "It’s a real problem that we face. It’s not insurmountable."

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(CNN) – On Wednesday, NASA officials announced a serious problem with the Kepler satellite, the world's most successful planet-finding machine.

Since its launch four years ago, Kepler has found more than 2,700 possible planets orbiting stars other than our Sun, of which more than 100 have been confirmed. A few of these exoplanets resemble the Earth in size or mass.

Recently, three Earth-like planets were even reported to be in the habitable zone: close enough to the star they orbit that water is liquid, yet not so close that it is boiling. Planets with liquid water may well harbor life.

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A meteoroid struck the surface of the moon recently, causing an explosion that was visible on Earth without the aid of a telescope, NASA reported Friday. But don't be alarmed if you didn't see it; it only lasted about a second.

"It exploded in a flash nearly 10 times as bright as anything we've ever seen before," said Bill Cooke, of NASA's Meteoroid Environment Office.

NASA astronomers have been monitoring the moon for the past eight years, looking for explosions caused by meteoroids hitting the lunar surface. It's part of a program to find new fields of space debris that could hit Earth. NASA says it sees hundreds of detectable lunar meteoroid impacts a year.

Sometimes technical science experiments lead to amazingly beautiful imagery. Princeton University's annual Art of Science competition collects some tantalizing examples of the intersection between science and art.

Click through the gallery to see some of the contenders.

Neuroscientists love Aplysia. They are a type of sea slug that grows to be about a foot long. With only 20,000 nerve cells - compared with about 100 billion found in the human brain - Aplysia are the perfect lab animals for brain researchers hoping to isolate a crucial connection.

Plus, "they're just attractive to look at," says Dr. Eric Kandel, a biochemistry and biophysics professor at Columbia University.

Kandel won the 2000 Nobel Prize in Physiology or Medicine for his work with Aplysia - or more specifically, for his work on the biological mechanisms of memory storage.

For decades, Kandel has studied how we create short-term and long-term memories at the molecular level. His work has shown what genes are changed during the learning process, how these genes are altered and how the changes contribute to the growth of new connections in the brain.

CNN spoke with Kandel about his research and why he's fascinated by the human brain. The following interview has been edited for brevity and clarity:

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The future of NASA's planet-hunting Kepler space observatory was in question Wednesday after a part that helps aim the spacecraft stopped working, the U.S. space agency said.

Controllers found Tuesday that Kepler had gone into a "safe mode" and one of the reaction wheels needed to orient the spacecraft would not spin, Associate NASA Administrator John Grunsfeld told reporters. NASA engineers are trying to figure out whether they can get the balky part back into service or whether they can resume control by another method, Grunsfeld said.

"We're not ready to call the mission over," he said. But at roughly 40 million miles from Earth, "Kepler is not in a place where I can go up and rescue it."

The Kepler mission has identified 132 planets beyond our solar system since its launch in 2009, leading scientists to believe that most stars in our galaxy have planets circling them. It has gone into a "safe mode" with its solar panels facing back at the sun, giving controllers intermittent communication with the craft as it spins.

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You wouldn't want to shower in it, but researchers have discovered pockets of water in a deep reservoir in Canada that may be up to 2.64 billion years old.

Researchers extracted the fluid from ancient rocks in a mine 1.5 miles underground in the area of Timmins, Ontario. In other mines, water has been found to support life, but scientists are still working to determine if there is life in this particular location. They say this is the oldest water found in such an environment.

We spoke with Chris Ballentine, professor of geochemistry at the University of Manchester in the United Kingdom, and senior author on this study, which published in the journal Nature. Here is an edited version of our email Q&A:

CNN: How did you find this ancient water?

Ballentine: My colleague in Toronto, Barbara Sherwood Lollar, project co-director, has been working on understanding the chemistry of these waters for many years. She suspected the water was very old because of the high levels of helium (which takes a long time to build up) contained in the water. I am developing new techniques to date underground water (an essential component when making safety cases for CO2 burial) and we decided to work together to put a proper age on these waters.

CNN: Do we think that there was life on Earth at that time?

Ballentine: Life was established on Earth by 3.5 billion years ago (Earth itself is 4.56 billion years old). The rocks containing the water we have analysed are about 2.7 billion years old. The Earth's surface would be teeming with very simple life - the ancestors of bacteria. Complex single-celled and multicelled organisms did not evolve until about 1.9 billion to 2.1 billion years ago. The water we have found is between 1.5 billion and 2.6 billion years in age.

CNN: Does this have any implications for life on other planets?

Ballentine: The system we have found is truly ancient and can support simple life. Our work tells us that Earth had a refuge for life during its earliest stages of formation - if life started there was a way for it to be preserved during continuing bombardment by meteorites that would make the surface of Earth barren - and could push back the time when life could have formed on Earth.

Equally on somewhere like Mars, any life that formed could have found its way into similar pockets of water in the Martian crust, and our work shows that these pockets of water can survive and provide a place for the life to have survived long after the surface of Mars lost its water and became sterile.

CNN: Can you describe the environment in which this was found?

Ballentine: These are waters that come out of the rock from exploration boreholes deep in the copper-zinc mine. The samples we have collected pour out of only some boreholes, but they can flow for months. The environment is dark, dusty, very noisy and hot.

CNN: Is it drinkable?

Ballentine: Alas not. The water is crystal clear when it first comes out of the rock and looks very tempting, bubbling with gas. But actually it is too salty to drink (it is a brine), and the gas instead of carbon dioxide is a mixture of methane, hydrogen, nitrogen and helium!

But what about the world itself? Just like us, Earth doesn't stay the same. Some of the changes have been beneficial, while others are quite troubling.

Now a partnership between Google, NASA and Time is revealing how our planet has radically changed over the decades.

The new TIME Timelapse website allows users to view how the Earth has altered through millions of time-lapsed satellite images.

With a few clicks, you can learn how climate change, urban expansion and population growth have modified the planet.

Click on the above video to learn about Timelapse and get a taste of what you will find on the website.

A video of the Canadian astronaut singing David Bowie's "Space Oddity" from the International Space Station has been zipping around the Web at light speed since it was posted Sunday. The five-minute clip features Hadfield singing a modified version of the tune and strumming an acoustic guitar while floating through a space module, more than 200 miles above the Earth.

By Monday morning, it had more than 1 million views on YouTube, 3,000 comments on Reddit and was being widely shared across social networks.

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In some ways, it's just a number, but it's a big number with enormous implications.

For the first time, scientists measured an average concentration of atmospheric carbon dioxide of 400 parts per million in Mauna Loa, Hawaii, where the National Oceanic and Atmospheric Administration observatory is located, on Thursday.

"Most experts that really study CO2 amounts estimate that we haven't seen that amount of CO2 in our atmosphere in about 3 million years," said J. Marshall Shepherd, climate change expert and professor at the University of Georgia. In other words, modern humans have never seen carbon dioxide in these proportions before.

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