| Our home, the planet Earth, may seem pretty big, but it is just one planet of many others that make up the universe.
The universe includes stars, meteorites, asteroids, and much more. Although scientists have learned a lot about space beyond Earth, there are still many things that remain
a mystery. How big is the universe? Is there life on other planets? These are just some of the unanswered questions about space. As our technology becomes more advanced, we
are finding more and more of these answers.
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The Solar System
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A solar system consists of a star in the center, with other planets or objects
revolving around it because of its gravitational force. Just like an object
dropped falls to the ground because of gravity, the planets are drawn to the
sun: In fact, they're always falling toward the sun, but since they're also
moving sideways, they fall sideways and don't get closer to the sun. Our solar
system is one of many. It consists of the sun (a star) and eight major planets
that revolve around it. It is part of a galaxy, a group of millions of stars
that are also held together by gravity. Our galaxy, the Milky Way, consists of
more than 100 billion stars! Some of those stars are centers of solar systems of
their own and have planets or asteroids surrounding them. |
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Stars
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Stars look like faraway specks of light when we look up at the night sky. Close
up, however, they are massive balls of bright, fiery gasses, mostly hydrogen and
helium. Our sun is the closest star to Earth. There are several types of stars.
Some are small and emit blue light; they have cooler temperatures and longer
life spans that can last billions of years. Others are hotter and larger and
have shorter life spans lasting only a few million years. Cooler stars last
longer because they don't use up all of their fuel as quickly. Stars start out
as nebulae, or clouds of gas and dust, and nuclear reactions from the gases are
what produce the energy and light that appears as a sparkle. Stars will end
either as white dwarves, neutron stars, or black holes, depending on their mass
and heat. |
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Groups of stars that are seen together in the night sky are referred to as
constellations. You may have heard of the Little Dipper, Big Dipper, or Orion's
Belt. These are all famous constellations that can be seen up above in different
parts of the sky depending on Earth's position. |
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Comets
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Comets look like snowballs flying through the sky. They are collections of
particles that release gas and dust as they shoot by. Some comets can be seen on
a regular basis in the inner solar system, within our view. Others exist beyond
our solar system in an area past Pluto's orbit called the Oort Cloud. Comets are
thought to be left over from the Big Bang, when the universe was created. |
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Comets contain a nucleus, which is made of rock, ice, dust, and other frozen or
hard particles, and a coma, which is the stuff surrounding the nucleus. The coma
contains gases that are warming and being emitted from the comet as it gets
closer to the sun. Many comets, but not all, also have a tail. |
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Planets
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Our solar system has eight major planets: Mercury, Venus, Earth, Mars, Jupiter,
Saturn, Uranus, and Neptune. Planets are bodies in space, either rocky or
gaseous, that orbit a sun and also have their own gravitational pull. Although
there are only a handful of planets in our solar system, scientists believe
there are more than 50 sextillion planets in the universe: That's 50 billion
trillion planets! About 100 billion of those are believed to be similar to
Earth. |
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Apart from the eight main planets in our system, there are also many dwarf
planets. Dwarf planets also revolve around the sun, but they are smaller and
don't meet the full definition of a planet. Pluto, once classified as a planet,
is now considered a dwarf planet. |
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The Sun
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The sun is the center of our solar system. It is what makes life for us possible
on Earth. Because of its heat, the gases and elements present on Earth could
combine to create life billions of years ago. The sun is responsible for day and
night, hot and cold, and the seasons, which all depend on where we are on Earth
and what part of Earth is facing the sun. |
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Although the sun is not the largest known star, it is quite a bit bigger than
average stars found in the universe. It is about 110 times wider than Earth, and
more than a million Earths could fit inside it. It is mostly made up of the
gasses hydrogen and helium, and continuous nuclear fusion reactions keep the sun
shining bright and providing heat and light to Earth. The sun has used up
roughly half of its energy since its birth, and it should continue burning for
the next 5 billion years. |
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The Moon
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The moon orbits Earth. It is about 239,000 miles away from Earth at any given
moment. It is made up of a core, mantle, and crust. Only one side of the moon,
called the "near side," ever faces Earth. The other side, called the "far side"
or "dark side," does not face Earth. |
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The moon affects the Earth in several ways. Its gravitational pull causes tides
in the ocean. Its reflection of light from the sun allows Earth to receive some
light even at night. Scientists differ in their views on how the moon was
formed. Some believe it formed separately from Earth, and others think it is the
result of a collision between Earth and another small planet many millions of
years ago. |
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Meteorites
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Meteors, similar to comets, appear as flashes of light in the sky. Also referred
to as shooting stars, they result from debris in space coming into Earth's
atmosphere and burning up in the process. The debris is often leftover pieces
from a comet, asteroid, or other celestial body. If the chunk of debris
successfully passes through the atmosphere and lands on Earth, what's left is
called a meteorite. Thousands of meteorites make it to Earth's surface each
year, although we don't find a lot of them because they land in places like
bodies of water or forests. |
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Galaxies
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A galaxy is a group of stars and other matter held together by gravity. Our
solar system is part of a galaxy called the Milky Way, which contains billions
of stars. Our home in the Milky Way is inside one of its spiral arms. |
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Galaxies can take on four different shapes: spiral, like the Milky Way;
elliptical, or in an oval shape; lenticular, or disc-shaped; and irregular, not
like any of the other shapes. Galaxies are thought to have a black hole in their
center. |
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Retrieved from
http://www.e-aircraftsupply.com/articles/space-lessons-for-kids.aspx
on August 22, 2017 |
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44 Closest Stars and How They Compare to Our Sun
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Stars have captivated the imagination of humanity since the dawn of our
existence. We know that the closest star to Earth is the sun, but what about the
stars beyond our solar system? This infographic explores the 44 closest stars to
us, examining the size, luminosity, constellations, systems, and potential
planets of each star. |
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What Is the Closest Star to Earth After the Sun?
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The closest star to Earth besides the sun is Alpha Centauri, at a staggering
distance of about 4.3 light years away. Alpha Centauri is actually a triple star
system, which includes Proxima Centauri at 4.244 light years away, Alpha
Centauri A at 4.365 light years away, and Alpha Centauri B at 4.37 light years
away. So technically, Proxima Centauri is the nearest star. Alpha Centauri A is
the the largest and brightest star in the system. It is about 10% more massive,
22% larger, and 150% brighter than our sun.
The burning question is, does Alpha Centauri have planets? In 2016, scientists
announced the discovery of a super-Earth exoplanet orbiting our
closest stellar neighbor, Proxima Centauri, the smallest star of the system. The
planet Proxima Centauri b is believed to be a rocky and temperate world. The
(habitability of Proxima Centauri b) has not been established, but scientists
speculate that immense solar flares from
Proxima Centauri may make the planet incompatible with life. However, these
flares may be rare, or the planet could be inhabited by UV-resistant organisms.
How long does it take to travel to Alpha Centauri? Alpha Centauri is 25.6
trillion miles away, or more than 276,00 times the distance from Earth to the
sun. A conventional
space rocket traveling
at 17,600 mph would take about 165,000 years to reach Alpha Centauri. At light
speed, it would take approximately 4 years to reach Alpha Centauri … but
unfortunately, we can’t travel that fast. In fact, our current understanding of
physics and the natural world suggests that we will never be able to achieve
light-speed or faster-than-light travel. So how will we get to Alpha Centauri?
The
Breakthrough
Starshot Project plans to launch ultra-light nanocrafts toward
Alpha Centauri. Equipped with lightsails, they would be propelled through space
by a ground-based light beamer. They would have the potential to fly by Alpha
Centauri in just more than 20 years, capturing images of the planet Proxima
Centauri b. So while we currently do not have a means of reaching the planet
physically, we may be able to gather more information on the closest planet
outside our solar system in the not-so-distant future.
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What Is the Brightest Star in the Sky?
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The brightest star visible from Earth is Sirius, also known as the “Dog
Star.” Its official name is Alpha Canis
Majoris because it is the most prominent star in the constellation Canis Major.
Sirius is about 25 times more luminous than the sun! Although it is white to
blue-white in color, Sirius is called a rainbow star because it often flickers
and twinkles a wide variety of colors. This twinkling is the product of the
starlight hitting Earth’s swirling and ever-changing atmosphere. |
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Retrieved from
44 Closest Stars and How They Compare to Our Sun
(alansfactoryoutlet.com)
on December 16, 2020 (Thank you, Hannah for the contribution!) |
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