The Universe and Solar System

Earth and Life Science

The Universe

The Universe is all of time and space and its contents. It includes planets, moons, minor

planets, stars, galaxies, the contents of intergalactic space, and all matter and energy. The observable universe is about

28 billion parsecs (91 billion light-years) in diameter. The size of the entire Universe is unknown, but there are many hypotheses

about the composition and evolution of the Universe.

Universe

The Big Bang theory is the prevailing cosmological model for

the universe from the earliest known periods through its subsequent large-

scale evolution. Detailed measurements of the

expansion rate of the universe place this moment at approximately

13.8 billion years ago, which is thus considered the age of the universe.

Big Bang Theory

The Big Bang did not occur as an explosion in the usual way one think about such things, despite

one might gather from its name. The universe did not expand into space, as space did not exist

before the universe, according to NASA. Instead, it is better to think of the Big Bang as the

simultaneous appearance of space everywhere in the universe. The universe has not expanded from any one spot since the Big Bang — rather, space itself has been stretching, and carrying matter

with it.

Big Bang Theory

After the initial expansion, the universe cooled sufficiently to allow the formation of subatomic particles, and later simple atoms. Giant clouds

of these primordial elements later coalesced through gravity in halos of dark matter, eventually forming the stars and galaxies visible today.

Big Bang Theory

Georges Henri Joseph Édouard Lemaître  was a

Belgian priest, astronomer and professor of physics at the Catholic

University of Leuven. He proposed the Big Bang Theory

Big Bang Theory

Creationism is the religious belief that the universe and life originated "from

specific acts of divine creation”, as opposed to the scientific conclusion that

they came about through natural processes.

Creationists base their beliefs on a literal reading of religious texts, including the

biblical Genesis creation myth and Islamic mythology from the Quran.

Creationism

Intelligent Design is the pseudoscientific view  that

"certain features of the universe and of living things are best explained by

an intelligent cause, not an undirected process such as natural

selection."

Intelligent Design

The Steady State Theory is  an alternative to the Big Bang model of the evolution of the universe. In the steady-state theory, the density of

matter in the expanding universe remains unchanged due to

a continuous creation of matter.

Steady State Theory

The 'holographic principle,' the idea that a universe with gravity can be described

by a quantum field theory in fewer dimensions, has been used for years as a

mathematical tool in strange curved spaces. New results suggest that the holographic principle also holds in flat

spaces. Our own universe could in fact be two dimensional and only appear three

dimensional -- just like a hologram.

Holographic Principle

According to NASA, the gravitational pull of small fluctuations in the density of matter back then gave rise to the vast web-like structure of stars and emptiness seen today. Dense regions pulled in more and more matter through gravity, and

the more massive they became, the more matter they could pull in through gravity,

forming stars, galaxies and larger structures known as clusters, super clusters, filaments and walls, with "great walls" of thousands of galaxies reaching more than a billion light years in length.

Structure

Less dense regions did not grow, evolving into area of seemingly

empty space called voids.

Structure

Atoms only make up 4.6% of the universe. Of the remainder, 23% is

made up of dark matter, which is likely composed of one or more species of

subatomic particles that interact very weakly with ordinary matter, and 72%

is made of dark energy, which apparently is driving the accelerating

expansion of the universe.

Content

In the 1920s, astronomer Edwin Hubble discovered the universe was not static. Rather, it was expanding, a find that revealed the universe was

apparently born in a Big Bang.

Expanding Universe

After that, it was long thought the gravity of matter in the universe was certain to slow the

expansion of the universe. Then, in 1998, the Hubble Space Telescope's observations of

very distant supernovae revealed that a long time ago, the universe was expanding more slowly

than it is today. In other words, the expansion of the universe was not slowing due to gravity, but instead inexplicably was accelerating. The name for the unknown force driving this accelerating expansion is dark energy, and it remains one of

the greatest mysteries in science.

Expanding Universe

The Solar System

A solar system is a star and all of the objects

that travel around it —  planets, moons,

asteroids, and meteoroids. Most stars host their own planets, so there are likely tens of billions of other solar systems in the Milky Way galaxy

alone.

Solar System

The solar system we call home is located in an outer spiral arm of the vast Milky Way galaxy. It consists of the sun (our star) and everything that orbits around it. This includes the eight planets and their natural

satellites (such as our moon), dwarf planets and their satellites, as well as asteroids, comets and countless

particles of smaller debris.

Size and Distance

The solar system extends much farther than the eight planets that

orbit the sun. The solar system also includes the Kuiper Belt that lies past

Neptune’s orbit. And beyond the fringes of the Kuiper Belt is the Oort

Cloud.

The Oort Cloud is a giant spherical shell that surrounds our solar

system. It has never been directly observed, but its existence is

predicted based on mathematical models and observations of comets that likely originate there. It is made

of icy pieces of space debris the sizes of mountains and sometimes

larger, orbiting our sun as far as 1.6 light years away.

Oort Cloud

Our solar system formed about 4.5 billion years ago from a dense cloud

of interstellar gas and dust. The cloud collapsed, possibly due to the shockwave of a nearby exploding

star, called a supernova. When this dust cloud collapsed, it formed a

solar nebula — a spinning, swirling disk of material.

Formation

At the center, gravity pulled more and more material in. Eventually the pressure in the core was so great

that hydrogen atoms began to combine and form helium, releasing

a tremendous amount of energy. With that, our sun was born, and it eventually amassed more than 99

percent of the available matter.

The order and arrangement of the planets and other bodies in our solar system is

due to the way the solar system formed. Nearest the sun, only rocky material

could withstand the heat when the solar system was young. For this reason, the

first four planets — Mercury, Venus, Earth and Mars — are terrestrial planets. They're small with solid, rocky surfaces.

Structure

Meanwhile, materials we are used to seeing as ice, liquid or gas settled in the outer regions of the young solar

system. Gravity pulled these materials together, and that is where we find gas giants Jupiter and Saturn and ice giants Uranus and Neptune.

The Sun

The sun at the heart of our solar system is a yellow dwarf star, a hot ball of glowing gases. Its gravity holds the solar system together, keeping everything from the

biggest planets to the smallest particles of debris in its orbit.

With the radius of 432,168.6 miles, our sun is not an especially large star

compared to the many other stars. Its distance from Earth is 93 million miles.

Mercury

Mercury's eccentric orbit takes the small planet as close as 47 million km (29 million miles) and as far as

70 million km (43 million miles) from the sun. Temperatures on Mercury's surface can reach 800

degrees Fahrenheit (430 degrees Celsius). Because the planet has no atmosphere to retain that heat, night time temperatures on the surface can drop to -290

degrees Fahrenheit (-180 degrees Celsius). Mercury speeds around the sun every 88 days, travelling through space at nearly 50 km (31 miles)

per second, faster than any other planet. One Mercury solar day (one day-night cycle) equals 175.97 Earth

days. Mercury's surface resembles that of Earth's Moon,

scarred by many impact craters resulting from collisions with meteoroids and comets.

Venus

Venus is the second planet from the sun and our closest planetary neighbor. 

With a radius of 3,760 miles (6,052 kilometers), Venus is roughly the same size as Earth, just

slightly smaller. From an average distance of 67 million miles (108 million kilometers), Venus is 0.7 astronomical units away from the sun. One astronomical unit (abbreviated as AU), is the

distance from the sun to Earth. From this distance, it takes sunlight 6 minutes to travel

from the sun to Venus. Venus makes a complete orbit around the sun (a

year in Venusian time) in 225 Earth days or slightly less than two Venusian day-night cycles.

Earth

Earth is the third planet from the sun and the fifth largest in the solar system. Just slightly

larger than nearby Venus, Earth is the biggest of the terrestrial planets. Our home planet is the

only planet in our solar system known to harbor living things.

With a radius of 3,959 miles (6,371 kilometers), Earth is the biggest of the terrestrial planets, and

the fifth largest planet overall.

Mars

Mars is a rocky body about half the size of Earth. As with the other terrestrial planets

- Mercury, Venus, and Earth - volcanoes, impact craters, crustal movement, and atmospheric

conditions such as dust storms have altered the surface of Mars.

Mars has two small moons, Phobos and Deimos, that may be captured asteroids. Potato-shaped,

they have too little mass for gravity to make them spherical. Phobos, the innermost moon, is

heavily cratered, with deep grooves on its surface.

Jupiter

Jupiter's stripes and swirls are cold, windy clouds of ammonia and water. The atmosphere is mostly

hydrogen and helium, and its iconic Great Red Spot is a giant storm bigger than Earth that has

raged for hundreds of years.  With a radius of 43,440.7 miles (69,911

kilometers), Jupiter is 11 times wider than Earth. If Earth were the size of a nickel, Jupiter would be

about as big as a basketball. Jupiter has the shortest day in the solar system. One day on Jupiter takes only about 10 hours (the

time it takes for Jupiter to rotate or spin around once), and Jupiter makes a complete orbit around the sun (a year in Jovian time) in about 12 Earth

years (4,333 Earth days).

Saturn

Like Jupiter, Saturn is made mostly of hydrogen and helium. Its volume is 755 times greater than that of

Earth. In the early 1980s, NASA's two Voyager spacecraft

revealed that Saturn's rings are made mostly of water ice, and they imaged "braided" rings,

ringlets, and "spokes" - dark features in the rings that form and initially circle the planet at different rates from that of the surrounding ring material.

Saturn's ring system extends hundreds of thousands of kilometers from the planet, yet the

vertical height is typically about 10 meters NASA has discovered 53 confirmed moons and another 9 provisional moons (for a possible total of

62 moons). (30 feet) in the main rings.

Uranus

The seventh planet from the sun with the third largest diameter in our solar system, Uranus is

very cold and windy. The ice giant is surrounded by 13 faint rings and 27 small moons as it rotates at a nearly 90-degree angle from the plane of its

orbit. This unique tilt makes Uranus appear to spin on its side, orbiting the sun like a rolling ball.

The first planet found with the aid of a telescope, Uranus was discovered in 1781 by astronomer

William Herschel, although he originally thought it was either a comet or a star. It was two years later that the object was universally accepted as a new planet, in part because of observations by

astronomer Johann Elert Bode.

With a radius of 15,759.2 miles (25,362 kilometers), Uranus is 4 times wider than Earth. If

Earth was the size of a nickel, Uranus would be about as big as a softball.

One day on Uranus takes about 17 hours (the time it takes for Uranus to rotate or spin once). And Uranus makes a complete orbit around the sun (a year in Uranian time) in about 84 Earth

years (30,687 Earth days). From an average distance of 1.8 billion miles (2.9

billion kilometers), Uranus is 19.8 astronomical units away from the sun. 

From this distance, it takes sunlight 2 hours and 40 minutes to travel from the sun to Uranus.

Neptune

The ice giant Neptune was the first planet located through mathematical predictions rather

than through regular observations of the sky. Nearly 4.5 billion kilometers (2.8 billion miles) from the Sun, Neptune orbits the Sun once every

165 years. It is invisible to the naked eye because of its extreme distance from Earth.

Neptune has 13 known moons, six of which were discovered by Voyager 2.

Neptune has six known rings. Voyager 2's observations confirmed that these unusual rings

are not uniform but have four thick regions (clumps of dust) called arcs. The rings are

thought to be relatively young and short-lived.

Besides those planets, we still have more objects that can be seen in our

solar system like small bodies such as the Dwarf Planets, Pluto, Ceres,

Asteroids, Comets, and Meteors and Meteorites. We also have the moons of different planets and the regions such as the Kupier Belt and the Oort Cloud.

TRIVIAS

VY Canis Majoris

The biggest/largest known stars in the Universe.

VY Canis Majoris (VY Cma) is a red hypergiant star located in the

constellation Canis Major. With as size of 2600 radii, it is the largest known star and also one of the

most luminous known. If you can fit 1 million planet Earths in

into our sun. You can fit 1 billion Suns into VY Canis Majoris.

VY Canis Majoris

OGLE-TR-122b

The smallest known star right now is the OGLE-TR-122b, a red dwarf star

that’s part of a binary stellar system. It is the smallest star to ever have its radius accurately measured; 0.12 solar radii. This works out to be 167,000 km, which is only 20% larger than Jupiter.

OGLE-TR-122b

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