What is a nebular?

Answer 1

A hypothesis concerning the origin of the solar system according to which a rotating nebula cooled and contracted, throwing off rings of matter that contracted into the planets and their moons, while the great mass of the condensing nebula became the sun.

Answer 2

A nebula is a vast cloud of gas and dust in outer space, where stars are born. These clouds can vary in size and shape, and they are illuminated by nearby stars or by the new stars forming within them.

Answer 3

The Solar Nebula Hypothesis is essentially the most prominent theory right now about how solar systems (ours in particular) are formed.

Gas and atoms formed in the cores of stars that had died existed in a giant cloud in space. Since everything that has mass is attracted to other things that have mass, these atoms were attracted to each other. As a result, density in certain areas of the cloud increased, this led to increased collisions of particles, which resulted in a temperature increase.

When the temperature exceeded 10000K a protostar could form. This means that there is a star with an exceptionally hot core and a cloud of gas and atoms surrounding it, an equatorial disk. The whole system is rotating, this prevents the entire equatorial disk from collapsing in.

This equatorial disk is what will eventually form planets. Solids that condense at a hot temperature are found in solid form closer to the Sun.

Solar wind sweeps away excess matter.

Answer 4

Also known as the nebular hypothesis, the solar nebula theory is a widely accepted model explaining the formation and evolution of the Solar System and throughout the universe. This states that stars form in massive, dense clouds of molecular hydrogen which matter coalesces into smaller, denser clumps inside that collapse and form into stars. This process has the ability to form new planets under the right circumstances, causing the formation of planetary systems to be thought of as a natural result of star formation that takes a process of at least 100 million years.

Answer 5

The Tidal Theory (or Chamberlain-Moulton Theory) suggests that a passing star pulled dust and debris from the forming Sun, leaving a string of debris that eventually formed the planets.

The Big Bang is the cosmological model of the initial conditions and subsequent development of theuniverse supported by the most comprehensive and accurate explanations from current scientific evidenceand observation. As used by cosmologists, the term Big Banggenerally refers to the idea that the universe has expanded from a primordial hot and dense initial condition at some finite time in the past, and continues toexpand to this day.

Answer 6

The solar nebula theory, also known as the nebular hypothesis, is the most widely accepted model explaining the formation and evolution of our solar system. It was originally applied to our solar system only but, this method of planetary system formation is now thought to hold true throughout the universe. The modern variant that is most accepted is the Solar Nebular Disk Model (SNDM).

According to SNDM stars form in massive, dense clouds of molecular hydrogen called giant molecular clouds(GMC). These clouds are gravitationally unstable, and matter coalesces into smaller, denser clumps inside. These clouds collapse and form stars. This can give birth to planets under the right circumstances, which are not fully understood. So, the formation of planetary systems is thought to be a natural result of star formation. The process is thought to take at least 100 million years.

According to SNDM, rocky planets form in the inner part of the protoplanetary disk where the temperature is high enough to prevent condensation of water ice and other substances into grains. This results in the coagulation of purely rocky grains and later into the formation of rocky planetesimals. After small planetesimals have formed, runaway accretion begins. Growth accelerates as mass accumulates. This leads to the growth of larger bodies by the destruction of smaller bodies. This lasts between 10,000 and 100,000 years and ends when the largest bodies exceed approximately 1,000 km in diameter. Next, oligarch accretion begins. Several hundred of the largest bodies(oligarchs), continue to accrete planetesimals. Only the oligarchs grow. Occasionally, oligarchs impact each other and form a larger body. The final result of the oligarchic stage is the formation of about 100 bodies between the size of the Moon and Mars. Last is the merger phase. This begins when the oligarchs become massive enough to perturb each other causing their orbits to become chaotic. This lasts for 10 to 100 million years and forms a limited number ofEarth sized bodies. Some of the oligarchs are thought to have brought water to Earth. The resulting rocky planets eventually settle into nearly stable orbits.

Scientists are still trying work out how to apply the solar nebula theory to the formation of giant planets. It is great to see that there are still challenges for our scientists. Unanswered questions mean unexplored frontiers.

We have written many articles about the solar nebula theory for Universe Today. Here's an article about how the solar system was formed, and here's an article about the new theory proposed for solar system formation.

If you'd like more info on the origin of the Solar System, check out NASA's Solar System exploration page, and here's a link to NASA's Solar System Simulator.

We've also recorded a series of episodes of Astronomy Cast about the formation of the Solar System. Start here, Episode 174: Mysteries of the Solar System, Part 1.

Answer 7

Otherwise known as "The Big Bang Theory", this is the best theory that Astronomers have come up with of the origin of not just the solar system, but the universe.

Rough "timeline" from Beginning-Now:

1. The Big Bang happens: all energy and matter in the universe is concentrated into a single point and becomes unstable. This explodes, releasing the trapped energy and begins a period of rapid expansion.

2. 10^-32 and 10^-6 seconds after the Big Bang: the universe begins as a hot, seething pool of energy. As it expands, it begins to cool somewhat, which allows the formation of quarks and other particles. Eventually, it cools enough for the quarks to clump into protons and neutrons.

3. Three seconds after Big Bang: protons and neutrons being to clump together and form hydrogen, helium, and lithium nuclei. It's still too hot for electrons to bind to nuclei from atoms. The Universe is still hot and dense, so the light can't pass from side to side.

4. 10,000 years later: the Universe becomes transparent and light beings to shine. Light is still present in form of cosmic background.

5. 300,000 years later: Universe begins to expand and cool. Electrons are able to bind to nuclei (finally!), and form stable atoms. This is the matter dominated era of the Universe.

6. 300 million years later: galaxies and stars start to form.

7. 13.7 billion years later: now!

Predictions for the future:

1. 100 trillion years from now: if Universe continues to expand, stars will burn out and the Universe will dim. The galaxies will collapse into black holes and those evaporte through a process called hawking radiation. What's left of the universe is devoid of matter and packed with low frequency energy-effective dead.

2. 100 billion years later: galaxy eventually stops expanding and starts to collapse. The Big Crunch happens (the Universe eventually collapses into a single point).

The best data we have now suggests this Universe will keep on expanding.

Answer 8

theory of the origin of the solar system according to which a rotating nebula cooled and contracted, throwing off rings of matter that contracted into the planets and their moons, while the great mass of the condensing nebula became the sun. a cloudy spot on the cornea

Answer 9

A 'Nebular' is a diffuse mass of interstellar dust or gas or both, visible as luminous patches or areas of darkness depending on the way the mass absorbs or reflects incident radiation.
I do hope that I helped you some. Have a great day!

Answer 10

Between 1940 and 1955 the German astronomer Carl f. von Weizsaccker, the Dutch-American astronomer Gerald P. Kuiper and the U. S. chemist Harold C. Urey worked out a theory that attempted to account for all the characteristics of the solar system that need to be explained. According to their dust-cloud theory, the solar system was formed from a slowly rotating cloud of dust and gas that contracted and started to rotate faster in its outer parts, where eddies formed. These eddies were small near the center of the cloud and larger at greater distances from the center. The distances corresponded more or less to the Titius-Bode relation.

As the clouds cooled, materials coagulated near the edges of the eddies and eventually formed planets and asteroids, all moving in the same direction. The slowly rotating central part of the cloud condensed and formed the sun, and the sun's central temperature rose as gravity further compressed the material. When nuclear reactions eventually began in the suns interior, about 5 billion years ago, much of the nearby gas was blown away by the pressure of the sun's emitted light. Nevertheless the earthy retained an atmosphere consisting of methane, ammonia, carbon monoxide, water vapor, and nitrogen, with perhaps some hydrogen. In this primitive atmosphere and in the seas below it, organic compounds were formed that eventually resulted in living organisms. The organisms evolved in the next 2 billion years into higher plants and animals, and photosynthesis by plants and the weathering of rock produced the oxygen in the earth's atmosphere.

Although free gases near the sun were blown outward 4 to 5 billion years ago, according to the dust-cloud theory, the giant planets were too distant to be much affected. They are large, therefore, and contain a great amount of hydrogen. The comets, in turn, are thought to be the outer part of the primordial nebula, left behind as the inner part condensed to form the sun and the planets. The Dutch astronomer J. H. Oort speculated that this material condensed into chunks that continue to move along with the sun through space. Now and then a chunk is perturbed and falls slowly toward the sun. As it is heated by sunlight, it grows a coma and tail.

The dust-cloud theory thus explains the solar system characteristics listed above. It is most weak in detailing the process whereby the planets and asteroids formed from solids that made up only a small percent of the primordial nebula. However, this is essentially a chemical problem, strongly dependent on the sequence or timing of events such as eddy formation, temperature changes, and the start of solar luminosity."