1. What Are Fermi Bubbles?
No, this is not a rare digestive disorder. The bubbles are massive,
mysterious structures that emanate from the Milky Ways center and extend
roughly 20,000 light-years above and below the galactic plane. The
strange phenomenon, first discovered in 2010, is made up of
super-high-energy gamma-ray and X-ray emissions, invisible to the naked
eye. Scientists have hypothesized that the gamma rays might be shock
waves from stars being consumed by the massive black hole at the center
of the galaxy.
2. Rectangular Galaxy
“Look, up in the sky! It’s a…rectangle?” Earlier this year,
astronomers spotted a celestial body, roughly 70 million light-years
away, with an appearance that is unique in the visible universe: The
galaxy LEDA 074886 is shaped more or less like a rectangle. While most
galaxies are shaped like discs, three-dimensional ellipses or irregular
blobs, this one seems to have a regular rectangle or diamond-shaped
appearance. Some have speculated that the shape results from the
collision of two spiral-shaped galaxies, but no one knows for now.
3. The Moon’s Magnetic Field
One of the moon’s greatest mysteries—why only some parts of the crust
seem to have a magnetic field—has intrigued astronomers for decades,
even inspiring the buried mythical “monolith” in the novel and film
2001: A Space Odyssey.
But some scientists finally think they may have an explanation. After
using a computer model to analyze the moon’s crust, researchers believe
the magnetism may be a relic of a 120-mile-wide asteroid that collided
with the moon’s southern pole about 4.5 billion years ago, scattering
magnetic material. Others, though, believe the magnetic field may be
related to other smaller, more recent impacts.
4. Why Do Pulsars Pulse?
Pulsars are distant, rapidly spinning neutron stars that emit a beam
of electromagnetic radiation at regular intervals, like a rotating
lighthouse beam sweeping over a shoreline. Although the first one was
discovered in 1967, scientists have for decades struggled to understand
what causes these stars to pulse—and, for that matter, what causes
pulsars to occasionally stop pulsing. In 2008, though, when one pulsar
suddenly shut off for 580 days, scientists’ observations allowed them to
determine that the “on” and “off” periods are somehow related to
magnetic currents slowing down the stars’ spin. Astronomers are still at
work trying to understand why these magnetic currents fluctuate in the
first place.
5. What Is Dark Matter?
Astrophysicists are currently trying to observe
the effects of dark energy,
which accounts for some 70 percent of the universe. But it's not the
only dark stuff in the cosmos: roughly 25 percent of it is made up of an
entirely separate material called dark matter. Completely invisible to
telescopes and the human eye, it neither emits nor absorbs visible light
(or any form of electromagnetic radiation), but its gravitational
effect is evident in the motions of galaxy clusters and individual
stars. Although dark matter has proven extremely difficult to study,
many scientists speculate that it might be composed of subatomic
particles that are fundamentally different from those that create the
matter we see around us.
6. Galactic Recycling
In recent years, astronomers have noticed that galaxies form new
stars at a rate that would seem to consume more matter than they
actually have inside them. The Milky Way, for example, appears to turn
about one sun’s worth of dust and gas into new stars every year, but it
doesn’t have enough spare matter to keep this up long-term. A new study
of distant galaxies might provide the answer: Astronomers noticed gas
that had been expelled by the galaxies flowing back in to the center. If
the galaxies recycle this gas to produce new stars, it might be a piece
of the puzzle in solving the question of the missing raw matter.
7. Where Is All the Lithium?
Models of the Big Bang indicate that the element lithium should be
abundant throughout the universe. The mystery, in this case, is pretty
straightforward: it doesn’t. Observations of ancient stars, formed from
material most similar to that produced by the Big Bang, reveal amounts
of lithium two to three times lower than predicted by the theoretical
models. New research indicates that some of this lithium may be mixed
into the center of stars, out of view of our telescopes, while theorists
suggest that axions, hypothetical subatomic particles, may have
absorbed protons and reduced the amount of lithium created in the period
just after the Big Bang.
8. Is There Anybody Out There?
In 1961, astrophysicist Frank Drake devised a highly controversial
equation: By multiplying together a series of terms relating to the
probability of extraterrestrial life (the rate of star formation in the
universe, the fraction of stars with planets, the fraction of planets
with conditions suitable for life, etc.) he surmised that the existence
of intelligent life on other planets is extremely likely. One problem:
Roswell conspiracy theorists notwithstanding, we haven’t heard from any
aliens to date. Recent discoveries of distant planets that could
theoretically harbor life, though, have raised hopes that we might
detect extraterrestrials if we just keep looking.
9. How Will the Universe End? [Warning, Potential Spoiler Alert!]
We now believe the universe started with the Big Bang. But how will
it end? Based on a number of factors, theorists conclude that the fate
of the universe could take one of several wildly different forms. If the
amount of dark energy is not enough to resist the compressing force of
gravity, the entire universe could collapse into a singular point—a
mirror image of the Big Bang, known as the Big Crunch. Recent findings,
though, indicate a Big Crunch is less likely than a Big Chill, in which
dark energy forces the universe into a slow, gradual expansion and all
that remains are burned-out stars and dead planets, hovering at
temperatures barely above absolute zero. If enough dark energy is
present to overwhelm all other forces, a Big Rip scenario could occur,
in which all galaxies, stars and even atoms are torn apart.
10. Across the Multiverse
Theoretical physicists speculate that our universe may not be the
only one of its kind. The idea is that our universe exists within a
bubble, and multiple alternative universes are contained within their
own distinct bubbles. In these other universes, the physical
constants—and even the laws of physics—may differ drastically. Despite
the theory's resemblance to science fiction, astronomers are now looking
for physical evidence: Disc-shaped patterns in the cosmic background
radiation left over from the Big Bang, which could indicate collisions
with other universes.
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