What Is Fossil Fuel?

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What is fossil fuel and why is it called that?Geoffrey Widdison:

The term "fossil fuel" is a bit of a misnomer. It refers to fuels that come from ancient life forms that lived long ago (on the order of millions of years) and have remained in the ground for eons, which we're now burning. The primary fossil fuels are coal, petroleum and natural gas. All of these were produced from the biomass of plants and animals that lived a very, very, very long time ago. That matter has changed over time to create these flammable and abundant fuels, which we're now burning in huge quantities.

The reason they're called fossil fuels is actually a bit strange. Fossils are mineralized remains of ancient plants and animals. They're our primary way of studying life forms that lived millions of years ago. But actual fossils have nothing to do with any of the fuels. The term "fossil" has come to be used as slang for anything particularly ancient, even though that's not the original meaning of the word. As a result, these fuel sources that come from ancient plants and animals are referred to with that word, even though no actual fossils are involved.

The reason fossil fuels, as a class, are so important is because they're non-renewable. Once a fossil fuel is burned, it won't be replaced for millions of years (or possibly ever, as the processes that created them may no longer work the same way). That means that when we run out of a fossil fuel, it's gone forever. If we have nothing to replace it, then we're in trouble. The other impact is that there's a huge amount of carbon locked up in the fossil fuels. All of this carbon has sat in the earth for an unimaginably long time. As we burn it, we're releasing this carbon into the atmosphere, in the form of carbon dioxide, which causes serious environmental problems.

This post originally appeared on Quora. Click here to view.

Why Are Sloths So Slow?

Sloths have little problem holding still for nature photographers.
Sloths have little problem holding still for nature photographers.
Geoview/iStock via Getty Images

When it comes to physical activity, few animals have as maligned a reputation as the sloth. The six sloth species, which call Brazil and Panama home, move with no urgency, having seemingly adapted to an existence that allows for a life lived in slow motion. But what makes sloths so sedate? And what horrible, poop-related price must they pay in order to maintain life in the slow lane?

According to HowStuffWorks, the sloth’s limited movements are primarily the result of their diet. Residing mainly in the canopy vines of Central and South American forests, sloths dine out on leaves, fruits, and buds. With virtually no fat or protein, sloths conserve energy by taking a leisurely approach to life. On average, a sloth will climb or travel roughly 125 feet per day. On land, it takes them roughly one minute to move just one foot.

A sloth’s digestive system matches their locomotion. After munching leaves using their lips—they have no incisors—it can take up to a month for their meals to be fully digested. And a sloth's metabolic rate is 40 to 45 percent slower than most mammals' to help compensate for their low caloric intake. With so little fuel to burn, a sloth makes the most of it.

Deliberate movement shouldn’t be confused for weakness, however. Sloths can hang from branches for hours, showing off some impressive stamina. And because they spend most of their time high up in trees, they have no need for rapid movement to evade predators.

There is, however, one major downside to the sloth's leisurely lifestyle. Owing to their meager diet, they typically only have to poop once per week. Like going in a public bathroom, this can be a stressful event, as it means going to the ground and risking detection by predators—which puts their lives on the line. Worse, that slow bowel motility means they’re trying to push out nearly one-third of their body weight in feces at a time. It's something to consider the next time you feel envious of their chill lifestyle.

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Are Any of the Scientific Instruments Left on the Moon By the Apollo Astronauts Still Functional?

Apollo 11 astronaut Neil Armstrong left the first footprint on the Moon on July 20, 1969.
Apollo 11 astronaut Neil Armstrong left the first footprint on the Moon on July 20, 1969.
Heritage Space/Heritage Images/Getty Images

C Stuart Hardwick:

The retroreflectors left as part of the Apollo Lunar Ranging Experiment are still fully functional, though their reflective efficiency has diminished over the years.

This deterioration is actually now delivering valuable data. The deterioration has multiple causes including micrometeorite impacts and dust deposition on the reflector surface, and chemical degradation of the mirror surface on the underside—among other things.

As technology has advanced, ground station sensitivity has been repeatedly upgraded faster than the reflectors have deteriorated. As a result, measurements have gotten better, not worse, and measurements of the degradation itself have, among other things, lent support to the idea that static electric charge gives the moon an ephemeral periodic near-surface pseudo-atmosphere of electrically levitating dust.

No other Apollo experiments on the moon remain functional. All the missions except the first included experiment packages powered by radiothermoelectric generators (RTGs), which operated until they were ordered to shut down on September 30, 1977. This was done to save money, but also because by then the RTGs could no longer power the transmitters or any instruments, and the control room used to maintain contact was needed for other purposes.

Because of fears that some problem might force Apollo 11 to abort back to orbit soon after landing, Apollo 11 deployed a simplified experiment package including a solar-powered seismometer which failed after 21 days.

This post originally appeared on Quora. Click here to view.

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