- The current theory of the origin of the universe is the Big Bang, which
holds that the universe began as an explosion that filled all space.
- When
we look at quasars which are 10-15 billion light years away, we are looking
10-15 billion years into the past. Pretty amazing, right?
- Many astronomers believe
that quasars are the most distant objects yet detected in the universe. Quasars
give off enormous amounts of energy - they can be a trillion times brighter
than the Sun!.Quasars
might be the ancestors of all galaxies, the violent beginnings of us all.
Universe consists of 4 percent “normal” atoms (the stuff we are made of),
23percent dark matter, and 73
percent dark energy.
Expansion
of the universe is accelerating.
Large amount of evidence suggests that the center of our Galaxy harbors a
massive black hole.Galactic centre appears to be the location of a black
hole of several million solar masses.At the centre of every galaxy contains a massive black hole.
Each galaxy contains several hundred billion stars, typically about 100
times as many
stars as there are people on our planet.
If the
Earth were compressed to the
size of a marble—yet retained its
current mass—a velocity greater
than the speed of light would be
required to escape its marblesized
surface. Such an object
would be, effectively, a black
hole.
All supernova explosion does not lead to black hole.
We recognize two types of supernovae. Type I supernovae contain little
hydrogen, whereas Type II are rich in that element. Only Type II
supernovae are associated with the core collapse of high-mass stars and forms black hole. Type I
supernovae are associated with our friends the white dwarfs and Neutron stars.- A
giant is a star with a radius between 10 and 100 times that of the Sun.A
supergiant is a star with a radius more than 100 times that of the Sun. Stars
of up to 1,000 solar radii are known.A dwarf star has a radius similar to or smaller
than the Sun.
- To
produce energy, hydrogen atoms in the Sun’s core plow into one another and thereby
create helium atoms. In the process, a little mass is converted into energy.
That little bit of energy for each collision equates to enormous amounts of
energy when we count all of the collisions that occur in the core of the Sun.
With this energy source, the Sun is expected to last not 1,000 years or even
100 million years, but about 8 to 10 billion years, typical for a star with the
Sun’s mass.
The Sun doesn’t keep its energy to itself. Rather this energy flows away
in the form
of electromagnetic radiation and particles. The
particles (mostly electrons and protons)
don’t move nearly as fast as the radiation, which
escapes the surface of the Sun
at the speed of light, but they move fast
nevertheless—at more than 300 miles per
second (500 km/s). This swiftly moving particle stream
we call the solar wind. the
gases are sufficiently hot to escape the tremendous
gravitational pull of the Sun.
The
surface of Earth is protected from this wind by its
magnetosphere, the magnetic field,
a kind of “cocoon,” generated by the rotation of
charged material in Earth’s molten
core. Similar fields are created around many other
planets, which also have molten
core material. The magnetosphere either deflects or captures charged
particles from the solar wind.
Most
asteroids are rather small; it is estimated that there are 1 million with
diameters greater than 1 km. Some, perhaps 250, have diameters of at least
100 km, while about 30 have diameters of more than 200 km. All of these
planets and asteroids are the debris from the formation of the Sun that coalesced slowly through the mutual attraction of gravity.
Rings around planets are indeed made up of particles, primarily of water ice.
Ganymede
is the largest moon in the solar system (bigger than the planet Mercury)
orbiting Jupiter.
There are 62 moons (at least)
for Jupiter, 60 for Saturn,
27 for Uranus, and 13 for Neptune.
-
The Moon is in a synchronous orbit around Earth; that is, it rotates once
on its axis every 27.3 days, which is the same time it takes to complete one orbit around Earth. Thus synchronized, we see only one side of the Moon.
Clearly visible on images produced by Martian probes are runoff and outflow channels, which are believed to be dry riverbeds, evidence that
water once flowed as a liquid on Mars.
The Martian surface contains large amounts of iron oxide, red and rusting that’s why it’s a red
planets.
The rotation period of venus is negative because the rotation of Venus is
retrograde; that is, the planet rotates on its axis in the opposite direction
from the other planets.The rotation period of Uranus is negative because it is retrograde; like Venus, it rotates on its axis in the
opposite direction from the other planets.If at 59
days, Mercury rotates on its axis slowly, Venus is even more sluggish,
consuming 243 Earth days to accomplish a single spin.
all the planets (terrestrial and jovian) spin counterclockwise—except for
Venus, which spins clockwise.
The gravitational field of a passing star from time to time deflects a comet out of its orbit within
the Oort Cloud, sending it on a path to the inner
solar system.
After a short-period or long-period comet is kicked out of its Kuiper Belt
or Oort
Cloud home, it assumes its
eccentric orbit indefinitely. It can’t go home again.It may then collides with the planets.
Mercury and venus have 0 moons,earth has 1,mars has 2,Jupiter
62,Saturn 60,Uranus 27 and Neptune has 13 moons.
Jupiter,the
largest planet in the solar system, is over 300 times the mass of Earth, but
the Sun is more than a thousand times more massive than Jupiter and about
300,000 times more massive than Earth.
Astronomical unit (A.U.), which is the average distance between Earth and
the Sun—that is, 149,603,500 kilometers or 92,754,170 miles.
Pluto, long counted as the ninth planet, was
recently downgraded from a full-fledged planet to a mere “dwarf planet.”
Right now, the fastest rockets are capable of achieving 13.333 km/s or 30,000 miles per hour (48,000 km/h),
or 262,980,000 miles per year (423,134,820 km/y).
Maybe—someday—technology will enable us at least
to approach the speed of light.
Light travels at extraordinary speeds (about 984,000,000 feet—300,000,000 meters—every second), but the
light that we now see from many objects in the sky
left those sources thousands, millions,
or even billions of years ago. Remember
the Andromeda galaxy? We can see it, but the photons
of light we just received from
the galaxy are 2 million years old. Now that’s a long commute!.
we
are not alone in this universe….there may be another planet,revolving a star in the universe,which may contain lives.
To a distant observer, clocks
near a black hole appear to tick more slowly than those further away from the
black hole. Due to
this effect, known as gravitational time
dilation, an object falling into a black hole appears to slow down as it
approaches the event horizon, taking an infinite time to reach it. At the same time, all processes on this object slow down, for a
fixed outside observer, causing emitted light to appear redder and dimmer, an
effect known as gravitational redshift. Eventually,
at a point just before it reaches the event horizon, the falling object becomes
so dim that it can no longer be seen.
On the other hand, an observer
falling into a black hole does not notice any of these effects as he crosses
the event horizon. According to his own clock, he crosses the event horizon
after a finite time without noting any singular behaviour. In particular, he is
unable to determine exactly when he crosses it, as it is impossible to
determine the location of the event horizon from local observations.
- Centre of the Universe is every where.
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