Space Mysteries-english

The funny thing about discoveries is that they often produce new mysteries, too.  Many remarkable space science findings generated puzzling problems for astronomers to look into. 

In some cases the puzzles are brand new. Other times a discovery merely confirms how little we knew. Either way, there's plenty for astronomers to do.

Here then are the Top  Space Mysteries that astronomers will be pondering:

1. Dark Energy

Nobody knows what the heck it is, but it is officially repulsive. And man is it powerful! More powerful than gravity, even. 

While gravity holds things together at the local level (and by local I mean within galaxies and even between them, forming galactic clusters) some unknown force is working behind the scenes and across the universe to pull everything apart. Scientists have only come to realize this dark force in recent years, by discovering that the universe is expanding at an ever-increasing pace. 

Having no clue what it is, they've labeled it dark energy. 

The past year was a good one for proving that dark energy is at work. Calculations have been refined: The repulsive force dominates the universe, comprising 65 percent of its makeup. 

(Similarly unseen and exotic dark matter makes up 30 percent of the universe, leaving us with a universe that contains just 5 percent normal matter and energy.)

Two curious ideas related to the accelerating expansion, both of which emerged in 2002: All galaxies are destined to become frozen in time or, perhaps, time never ends.

2. Water on Mars?

Mars simply will not give up its most coveted secrets. Ultimately, the big quest for NASA and all the Mars scientists is about whether there is life, but before that's answered, there is the question of liquid water, a requirement of life as we know it. 

Despite two major discoveries of water ice in 2002, nobody can figure out yet whether any of it might exist in the melted state. 

Meanwhile, clues mount. In one compelling study released in December, dark streaks on the surface were attributed to salty, running water. But many experts remain unconvinced. NASA's Odyssey spacecraft is circling Mars as you read this, hunting for more evidence.

3. The Murky, Mediocre Middle of the Milky Way

Something is eating at the black hole at the center of our galaxy. And whatever is bugging the gravity monster manifests as an utter lack of appetite. 

In October, astronomers announced they'd watched a star zip around the black hole that anchors the Milky Way, all but proving the impossible-to-see object is actually there. Meanwhile, the region around the black hole is an active place, as the Chandra X-ray Observatory showed early this year. 

However, the black hole is not devouring enough matter to generate the tremendous X-ray output seen with other supermassive black holes. Scientists are so far unable to fully explain the stark contrasts they've seen, this tremendous diversity in black hole behavior.

Hints emerged this year, however. A study in January suggested mergers between two black holes might serve as an on-off switch for the activity. Then observations announced in November showed two black holes involved in a pending merger. Astronomers now need to tie all this to a firm explanation of the differences between the mediocre output of our black hole and the brilliant illumination surrounding others in many distant galaxies.

4. The Origin of Life

Have you ever had one of those dreams where you try to run from a monster and your legs go 'round and 'round but you don't get anywhere? The quest to understand the origin of life isn't much different.

In fairness, it must be pointed out that there is little data to work with. Earth does not retain a record of what went on billions of years ago, when life got going.

Meanwhile, there is no shortage of wild ideas. Scientists now generally agree that life could survive a trip to Earth from Mars, in the belly of a rock kicked up by an asteroid impact. A study in November revealed why a Mars rock lands on Earth once a month, on average. A wilder idea, that bugs simply rain down from space inside comet dust, gained support from a second scientist in December, who claimed to have found some of these space bugs in Earth's atmosphere.

Most mainstream scientists, however, figure there's a good chance that life on Earth was cooked up in a soup of pre-biotic chemicals right here on the planet. The ingredients -- water and organic chemicals -- may well have come from space, but Earth likely acted as the incubator.

The answer (and a lot of well-funded researchers are asking the question and debating the possibilities) bears on how likely it is that life might have begun elsewhere, on Mars or around another star.

5. Lunar Secrets

No place beyond Earth is more well studied than the Moon. We went there, stomped around. Sifted the soil. Brought some rocks back. But the Moon still holds many secrets. The most profound might be rocks launched from Earth billions of years ago by asteroid impacts. 

These storehouses of terrestrial information have been presumed for years to exist on the Moon; this July an attempt was made to quantify them. The estimate: 11,000 pounds of Earth stuff sits within a few inches of the surface for every square mile on the Moon.

The rocks should hold information about the composition of the young Earth and its atmosphere, and possibly even the origin of life. This information is not available anywhere else because, unlike the Moon, Earth continually recycles its surface material, folding it inward and melting it beyond recognition.

Nobody can say for certain this stuff is there, or whether it can be retrieved, but researchers are optimistic.

"This [new study] gives us a compelling reason to go back -- to look at the Moon as a window to early Earth," said study leader John Armstrong of the University of Washington. He added that it would be the fastest and cheapest way to learn about planet's early years and the formation of the whole solar system.

6. The Enigmatic Sun

If you're looking for a career with a really bright future, become a solar physicist. Amazingly, we still don't fully understand the dynamics of the star we orbit.

New pictures of sunspots in 2002, the most detailed ever, revealed canal-like structures reaching from bright regions into the dark hearts of sunspots. The strange structures are fueled by the Sun's tremendous heat and magnetic energy, but beyond that, their generation is a mystery.

"Exactly what happens and why these kind of structures are formed, we don't know," said study member Dan Kiselman. 

And the Sun in general? "The amazing zoo of structures and dynamic phenomena on the Sun are not well understood in general, though they have been observed for a very long time," Kiselman said. Sounds like serious job security.

7. Age of the Universe 

Scientists pretty much agree on the general method by which the early universe evolved. But they start to argue when the topic of the universe's actual age comes up.

The age of the universe has been put at 12 billion to 15 billion years for some time now, but every few months a revision or refinement is announced. Hubble Telescope observations yielded in April an estimate of 13-14 billion years.

We can't say when a firm answer will be presented, but we can predict the likelihood of another estimate sometime in 2003.

(A related and even more vexing set of questions: What exactly happened at the beginning of the universe, and what existed before that instant? These are questions cosmologists will likely wrangle with forever, since no direct observations can be made of those time frames and therefore, presumably, no proof can come.)

8. Missing Planets

Imagine the surprise of a really smart scientist who runs the latest computer model, loaded with a decades-old, widely accepted theory about how our solar system formed, and the computer spits out a diagram with only seven planets.

Uranus and Neptune have been missing, in theory, for some time now. The problem arises because the standard model of planet formation requires material to crash together and stick over millions of years. Once a large core is built, gas can be attracted to create planets like Jupiter and Saturn. But out where Neptune and Uranus roam, there would never have been enough hard material for this to work.

This year, theorist Alan Boss of the Carnegie Institution of Washington put forth a radical new idea, a planet-formation mechanism that conveniently builds the two outer ice giants, too. Boss figures the four big planets in our solar system did not develop from rocky cores, as the standard model once held, but that they collapsed from large gas and dust clouds. 

To round out his theory, and the planets, Boss had to put our fledgling solar system in another part of space. He chose a region of intense star formation, so that the UV radiation from a nearby star could strip Uranus and Neptune down to fighting weight. The solar system then migrated to its present, more pleasant region of the galaxy.

All well and good, but other astronomers are very skeptical. We're left with an old theory that doesn't work and a new one that is, in the words of its creator, a wild idea.

Maybe, while some scientists are busy looking for planets around other stars, someone will figure out for sure how the planets in our own solar system were created!

Source:

Space.com