ASTRONOMICAL
MYSTERIES
3
1. Could a Distant, Dark Body
End Life on Earth?
If a nearby star
went supernova, a gamma ray burst erupted nearby, or a black hole or a stream
of anti matter somehow wandered into our neighborhood, it could spell disaster.
While astronomers say those events are unlikely, another dark distant
interloper could create havoc on earth by its mere presence. A number of astronomers suggest the Sun may have a hidden, dark
companion that periodically sends comets sunward, raining them down on the
inner solar system. Although we live in relative quite in cosmos danger lurks
in space even with an invisible dark object.
2. Is Jupiter a failed
star?
It
would need to be about 75 times its current mass to ignite nuclear fusion in
its core and become a star. Jupiter as the
largest planet in the solar system long before any spacecraft provided detailed
exploration. The planet’s mammoth size — 88,846 miles (142,984 kilometers) at
the equator — holds 2.5 times the mass of all the other planets combined. This
makes Jupiter the most dominant body in the solar system after the Sun. The
planet’s volume is so great that 1,321 Earths could fit inside it.
3. Why
Does Antimatter Exist?
Shortly after the Big Bang, the cosmos was awash in
particles. Not all of them were normal particles of matter, however.
Corresponding with each type of particle is an antiparticle with the same
mass and spin. The nature of our universe results from the fact that
matter exists in slightly more quantity than antimatter. The difference is
slight, however: For every billion particles of antimatter, there must have
been a billion and one particles of matter in the early universe. Everything
that exists — galaxies, stars, planets, trees, people — owes its existence to
the slight surplus of matter.
Anywhere high-energy
collisions take place, antimatter is sure to be there. The powerful black hole
in the center of the Milky Way produces an antimatter jet. The boundary where
the antimatter collides with normal matter produces gamma rays.Antiparticles
get made where the temperature is extremely high — for example, the event
horizon of a black hole. Should we ever get to the point of traveling deep into
space, hazards from antimatter, which annihilates matter when the two collide —
would pose a real and somewhat unpredictable hazard.
4.
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5.
What Creates Gravitational
Waves?
1916,
Albert Einstein revolutionized our understanding of the universe when he
published his general theory of relativity. In it, the German-born physicist
described the complex relationship between the fabric of space-time and
the mass of celestial bodies. Space-time is the combination of three spatial
directions (height, width, and depth) with the time dimension.
The easiest way to
interpret gravitational interactions, Einstein said, is to think of the
space-time continuum as a stretchable material that bends as massive objects
“sit” inside it. While this two-dimensional analogy does not represent what is
happening in four-dimensional space-time, it serves as a capable model. M assive objects also cause another effect in the fabric of
space-time. Just as a boat creates waves on a lake as it slices forward through
the water, stars and other bodies in the universe create ripples in the fabric
of space-time as they move. Astronomers call these ripples gravitational waves.
6.Where Do Cosmic Rays Come From?
Physicists initially believed cosmic rays
were gamma rays, high-energy radiation produced by radioactive decay. During
the 1930s, however, experiments revealed that cosmic rays are mostly charged
particles. In 1937, French physicist Pierre Auger (1899–1993) found that
extensive particle showers (called air showers) occur when cosmic rays collide
with particles high in the atmosphere, producing a cascade of electrons,
positrons, photons, muons (particles similar to electrons but 200 times as
massive), and other particles that reach Earth’s surface.
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7.What Happens When Black Holes Collide?
It turns
out a funny thing happens when black holes collide. They spiral toward each
other and merge into a single entity. In some cases, a gravitational
“slingshot” effect then violently whips them outside their host galaxies into
intergalactic space. The ejection mechanism results from a byproduct of the
merger: gravitational waves. The gravitational waves can actually kick the
merged black hole far away from the site of its merger. In 2017, astronomers
found compelling evidence of such a mechanism when they used Hubble to image
quasar 3C 186. Observations of the offset quasar suggested that it was
jettisoned from the core of its galaxy by gravitational waves produced by the
merger of two supermassive black holes.
8. After all, some 200 to 400 billion stars
inhabit our galaxy, and astronomers estimate at least 125 billion other
galaxies exist. That’s one heck of a number of stars in the universe — at least
25,000 billion billion. Looking at the nebular hypothesis, which describes how
the solar system formed, it seems clear most stars would form planets as their
protogenitor clouds collapsed. Yet, due to the immense distances, seeing other
planetary systems remained a supreme challenge for astronomers until the past two
decades.W ith the number of exoplanets growing
week by week, researchers plan new and ambitious projects to expand the number
of discoveries dramatically. Before Kepler, most exoplanets found were large
“hot Jupiters.” The satellite, though, found hoards of smaller worlds and even
spied a few possible Earth cousins. Current and future missions such as the
Transiting Exoplanet Survey Satellite (TESS), the CHaracterising ExOPlanet
Satellite (CHEOPS), and the Planetary Transits and Oscillations of stars (PLATO)
will use the transit method to further expand the number of exoplanet
discoveries. TESS, for example, will soon look across the entire sky to find
all exoplanets around dim red stars within a few hundred light-years from
Earth, as well as give astronomers targets for future missions that will search
for gases produced by life, like methane and carbon dioxide.
9. Why Did Mars Dry Out?
Years ago, astronomers detected signs of
Mars’ watery past. Early evidence came from imaging large numbers of winding
channels on the Red Planet.These images suggest abundant liquids of some type
flowed on the planet at some point in its history. In 1972, the Mariner 9
spacecraft orbited Mars and took photos of what appear to be dry riverbeds
scattered over the planet’s surface. T he clear
implication is that Mars had a watery past and, for some reason, dried out, but
not completely. Using images from the Mars Global Surveyor satellite, planetary
scientists Devon Burr, Alfred McEwen, and colleagues looked carefully at Marte
Vallis, a river channel that extends from Elysium Planitia into Amazonis
Planitia. The flows would have to be significant to leave surface features
because the temperatures and pressures on Mars’ surface today mean water
quickly evaporates once it reaches the surface. The climatic change may have shifted the planet
to a less hospitable place. Moreover, Mars cooled following this period of
volcanism. During the cooling, astronomers believe Mars’ magnetic field
dissipated because the planet’s molten iron core solidified.
10.Is Water
Necessary for Life?
This
works for planetary-exploration missions and for extrasolar-planet telescopes
like Kepler. For many years, planetary scientists and biologists have held fast
to one maxim: Water is essential for life. Great interest focuses on the
possibility of extraterrestrial life, even if it’s merely microbial. So, follow
the water to find where the big planetary-exploration dollars will be spent. L ife
in the universe, astronomers and biologists now admit, could be based on
completely different chemical systems than ours. The first thing to do is to
define what we mean by “life.” By definition, living things have several
properties that separate them from rocks and dirt. Living things on Earth are
arranged into cells. They are also highly organized, on different levels and
with different tasks. They take in energy from the environment and excrete
waste products. They exhibit homeostasis, stable internal conditions that are
required to stay alive. They grow and change, showing differentiation and
mutation. They also reproduce, passing genetic material to their descendants.
Anything in the universe that exhibits these characteristics would be
considered a living being. If liquids other than
water might help create and sustain life, which ones might they be? Water does
have an amazing number of properties that help support life. But could another
fluid — ammonia, methane, formamide, or sulfuric acid — create a place where
exotic life forms could flourish?
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