What conditions are required for life?

Strange as it may seem, there isn't really one standard definition of life. We can't say that life requires something as specific as breathing or growing; there's just too much variety to living things to nail down one specific criterion.

What we can do is talk about some things that all living things on Earth share: They're carbon-based; they require water; they use energy. Perhaps most important for survival, they can grow or reproduce in some way.

So is that all scientists and astrobiologists are looking for when searching for signs of life outside the Earth? Let's take a deeper look at what is required for life to exist.

As we just said, a main requirement is water, which is necessary for many chemical reactions [source: NASA]. Liquid water allows for chemicals to be transported or dissolved, so we do need the water to be between 59 and 239 degrees Fahrenheit (15 and 115 degrees Celsius) so it doesn't vaporize or freeze [source: NASA].

Energy -- either in light or chemical form -- is also required for life. Both forms fuel the metabolic reactions that allow life to reproduce. Along with energy, we must make sure that any planet has a protective atmosphere that keeps the radiation from a sun out, while still keeping the planet warm.

Of course, life also needs nutrients that will help sustain it. The atmosphere of a planet or moon can even provide these. Methane, for instance, can produce carbohydrates and fats, which might contribute to my mandatory-cheese-and-wine planet [source: NASA]. These systems need to be able to replenish nutrients, which is no problem if your planet has events like volcanic eruptions or weather systems that produce water.

But here's the rub: While scientists can pretty confidently assert those things might be necessary for life on Earth, we should remember that we're basing all our assumptions on, well, Earth. We can't know for sure if other planets or moons could be harboring a "life" form that doesn't require the same things Earth-bound systems do. In the meantime, we'll look for the planets with nutrients, energy and water.

Comments

Why Do We Scratch Our Heads When We're Thinking?

Some people believe that certain automatic gestures — like scratching our heads when we're thinking — are natural motions that were passed down to us from our caveman predecessors. JOSE LUIS PELAEZ INC./GETTY IMAGES If you've ever had the distinct pleasure of sourcing stock photos for any reason, you've likely come across a whole lot of laughing women eating salads alone . But you've also probably stumbled upon a truckload of people scratching their heads to symbolize confusion, deep thought and/or perhaps a bad case of seborrheic dermatitis — dandruff. Scalp dryness aside, how exactly did the head scratch come to symbolize intellectual processes? Some people believe that certain automatic gestures are simply natural, expressive motions our caveman predecessors passed down to us. "One popular explanation for any hand-to-head movements is that they're frustrated aggression — a reversion to the natural movements of our rock-throwing ancestors," wrote Sa...

Jackie Robinson in Reverse, Eddie Klep Integrated Negro Leagues

WASHINGTON President Bush presented the Congressional Gold Medal to the family of Jackie Robinson this week, in posthumous honor of the man who broke through major league baseball’s racial barrier in 1947. Unmentioned and unmourned was the late Eddie Klep, who crossed baseball’s color line a year earlier in the opposite direction. Klep was the first white man to play Negro League ball. A short-lived pioneer, he washed out in his first season as a Cleveland Buckeye. A few years later he was wearing the uniform of the Rockview (Pa.) State Prison baseball team. In talent, character and impact, he was no Jackie Robinson. But Eddie Klep’s exploits, such as they were, serve as a reminder that integration is a two-way street. Beyond the brave tales of celebrated black breakthroughs, the path toward racial progress is also adorned with intriguing stories of white Americans willing to go where others feared to tread, everyday people distinguishing themselves with simpl...

Spotify announces new partnership with Samsung - Finally Spotify will pose like Apple Music

Spotify co-founder and CEO Daniel Ek There's a new collaboration in the works. Early Friday morning, Spotify co-founder and CEO Daniel Ek (pictured) revealed through an online Q&A session that the music streaming service is partnering with smart-phone makers Samsung to "create a seamless music listening experience together for the user that would be hard for either of us to build alone". The streaming service will now be integrated into future Samsung phones, and will be the brand's main music player app. Another feature that will be available will be the synchronizing of Spotify accounts across multiple Samsung devices, from phones to TVs, tablets, speakers and watches. Ek commented on the feature, saying, "As you move from room to room, your devices will be aware of your location and prompt you to effortlessly transition your listening between them". Ek further went on to comment on Spotify's integration with Samsung, revealing that the partn...

The Art of Reading

Search This Blog