A solar system is a collection of bodiesrevolving around a star.These bodies include things like planets,moons and many other objects.Our particular Solar System consists of the Sun(our star), planets, moons (which orbitplanets), comets, meteors and asteroids.Today we will examine our Solar Systemstarting with the Sun, what it is and how itgot there.
The first question to be dealt with, how didthe Sun get there?To answer that we must start at the “beginning”.According to scientists and the “Big Bang” theory,our universe sprang into existence as a"singularity” around 13.7 billion years ago.This singularity is described as an infinitesimallysmall, infinitely hot, infinitely dense, something -a singularity. Where did it come from? We dontknow. Why did it appear? We dont know.
From the Big Bang, the universe expanded forover 9 billion years when the beginnings of ourSun occurred.Scientists believe that our Solar System wasformed about 4.6 billion years ago from thecollapse of a massive, rotating cloud ofgas, dust and ice called the Solar Nebula.The gas in this nebula was primarily hydrogenand helium, the dust was made up of thematerials that are found in rock, and the icewas water, methane, and ammonia.
As this Solar Nebula cloud collapsed, it formeda flat disk with most of its matter in the center.After about 10 million years, the hydrogen inthe center got hot enough to fuse and the Sunstarted to “shine.”
The particles within the flattened diskcollided fusing to form asteroid-shapedobjects.Some of these object hit one another andgrew in size.
As more particles coalesced and grew larger, planets, moons (which orbit planets), comets, meteors and asteroids were formed....and our Solar System came into being.
1. CoreAlthough the Sun is mostly just a ballof hydrogen and helium, it can bebroken down into distinct layerscaused by temperature and pressureincreases.
The core of the Sun is the source of allits energy.This energy is a result of the extremetemperatures and pressure found at thecenter of the Sun.In the core, the temperature is(15,000,000° C or 27,000,000° F) andthe pressure is 340 billion times Earthsair pressure at sea level.
The heat and pressure are so intensenuclear fusion reactions take place—hydrogen nuclei change into helium nuclei .The high temperature causes the hydrogennuclei to zing around wildly slamming intoone another at high speeds.As a result of these collisions, two hydrogennuclei fuse (join) to forming a helium nucleus.Tremendous amounts nergy is released in thisreaction.
Moving from the inside out from the core, thesecond layer of the Sun is called the radiative zone.Energy from the core of the Sun continually movesoutward to the surface. This region is slightly coolerthan the core and the energy can move by radiation—from one atom to the next.Energy makes its way very slowly through this layerof the Sun.
Once out of the radiation zone the helium andhydrogen are cooler so the energy, originallyproduced in the core, requires a different way tomove to the surface.The most efficient means of energy transfer isnow convection i.e. the convection zone.The cooler material near the top of the radiationzone sinks down pushing the hotter material up.As the hot material reaches the top of theconvection zone it begins to cool and sinks, andas it sinks it heats up again and will rise again—aconvection current.
The energy is transferred much faster byconvection than by radiation.
1. Core 2. Radiative 3. Convective zone zone4. Photosphere
The next layer in the Sun is thephotosphere, the only layer visible to us onEarth.Thephotosphereis the diskyou seewhenobservingthe Sun inthe sky. http://www.swpc.noaa.gov
When we look at the Sun there is adepth beyond which the gas is so densethat we can not see through itWe call the region where this happens theapparent surface, or the photosphere.It is the apparent surface because theSun is completely made of gases sothere is no hard surface like there is onearth.
Energy is transported through thephotosphere once again by radiation.Most of the light that we receive from theSun on earth is energy that was released inthe photosphere.
The layer above the photosphere is thechromosphere.Violent “flames” of hot gases called flareserupt in the chromosphere.Flares can be as large as the Earth and last upto several hours.Flares are very hot—twenty million degree Fhave been recorded.
The corona is the outer part of the Sunsatmosphere.The outer region of the corona stretches farinto space and emits a stream of electrons andprotons that travels slowly away from the Sun.This stream of charged particles is calledthe solar wind.
The corona isinvisible fromEarth. It canonly be seenduring a totalsolar eclipse.
The continuousrising and fallingof hot and coolbubbles from theconvective regionproduces apattern on thephotosphere thatis referred to asgranulation.Sunspots are dark spots on the photosphere,typically with the same diameter as the Earth.
Sunspots have coolertemperatures thanthe rest of thephotosphere.A sunspots life can beas short as an hour ortwo or as long asseveral months.The number of sunspots on the surface of the Sunincreases and decreases in a regular pattern, knownas the solar cycle, with a maximum number ofsunspots occurring every 11 years.
Prominences appear in the chromosphere.They areimmense arcsof glowinggases from theupperchromospherethat erupt intothe corona.Prominences are not as violent eruptions as flares.
Although the Sun is huge compared tothe other planets in our Solar System, itis only a medium-sized star.It is relatively small compared to many ofthe stars in the Universe.
Red Giant and Supergiant stars can be much larger than the Sun.
Before we go into theindividual planets in theSolar System, let’s considerhow planets in the solarsystem were formed.The same cloud thatformed the Sun now helpsus see how individual andvery different planetscame about.
We will start with the “cloud”. Near the centerof the cloud, rocky material condensed andthe four inner planets formed.
Planetary InteriorsThe heavier denser materials such as iron andnickel sank to the middle of the planets andthe lighter silicate materials floated to the top.
Solar winds swept lighter materials(hydrogen, helium, water , ammonia) outwardfrom the Sun.These icy substances formed the outer planets.The larger icy planets attracted the hydrogenand helium gas in the disc and grew in size—the giant gas planets.
Under the International Astronomical Union(IAU) definition of a planet, there are eightplanets in our Solar System. (Pluto is nolonger considered a major planet.)In order from the Sun are the four terrestrialplanets--Mercury, Venus, Earth and Mars andthe four gas giants-- Jupiter, Saturn, Uranusand Neptune.It also contains five dwarf planets—Ceres, Pluto(originally classified as the Solar System’s ninthplanet), Makemake, Haumea and Eris.)
As well as the major planets and their moons,our Solar System includes two large areaswhere numerous smaller bodies including thedwarf planets gather together—the asteroidbelt and the Kuiper belt.The Kuiper belt extends well beyond Uranus,the last major planet in the Solar System, andis home to three of the five dwarf planets.Objects in the Kuiper belt are largelyfrozen methane, ammonia and water.
The asteroid belt(shown in NASA NASAwhite), locatedbetween theorbits of MarsandJupiter, consistsof numerousirregularlyshaped bodiesmade of rock andmetals calledasteroids andone dwarf
The five dwarf planets—Ceres, Pluto(originally classified as the Solar System’sninth planet), Makemake, Haumea and Erisare much less familiar than the major planets.We will now take a brief look at each of them.
Ceres, the smallest of the dwarf planets, is madeof rock and the only one found in the asteroidbelt. Ceres as seen by the Hubble Space Telescope
Wikipedia CommonsMoon top left, Ceres bottom left—relative sizes
Pluto, the second largest dwarf planet, is thelargest member of the Kuiper belt.However, compared to the Earth’s moon Plutois relatively small—only one-fifth of the mass ofthe moon.Like other members of this belt, it is composedprimarily of rock and ice.Pluto has three moons--Charon, Hydra and Nix.
Pluto’s atmosphere is probably made up of of nitrogen and methane. These elements may exist as a gas when Pluto is closest to the Sun) and freeze as Pluto moves further away. The surface of Pluto is composed of about 98% nitrogenhttp://www.crh.noaa.gov with small amounts of methane and carbon monoxide.
Makemake is the third largest dwarf planetin the Solar System and is found in theKuiper belt. Wikipedia CommonsIt is about three-fourth the size ofPluto and itssurface is coveredwithmethane, ethaneand possiblelynitrogen ice. Makemake as seen by the Hubble Space Telescope
Haumea, with one-third the mass ofPluto, is another dwarf planet in the Kuiperbelt.Image ofHaumea andits twomoons. NASA
Eris, the largest known dwarf planet in theSolar System, orbits the Sun outside theKuiper belt. It is the ninth largest object to orbit the Sun.It has one knownmoon.On average, it is threetimes further from theSun than Pluto. Eris and its moon Hubble Space Telescope
Wikipedia CommonsSize comparison of Eris, Pluto, Makemake, and Haume(plus four other celestial objects) with Earth. Ceres isshown here because it is closer than Neptune.
This size comparison of the Sun’s planetshelps us see where Earth fits in.
The Sun is by far the biggest and mostmassive object in our solar system.It would take one hundred and nineEarths to fit across the Sun’s diameter.The interior of the Sun could hold over 1.3million Earths.
Another size comparison, this one makingEarth look a bit puny.
Even though the Sun is made mainlyhydrogen and helium, it is very massive..It makes up approximately 98% of the totalmass of the solar system.The Sun’s mass 333,000 times the massof the Earth.
As a result of this tremendous amount ofmass, the Sun has an enormous amount ofgravity.The gravity at the surface of the Sun is 28 timesthe gravity at the surface of the EarthSo if you weighed 100 pounds on Earth, youwould weigh 2800 pounds on the surface ofthe Sun. Your body would be so heavy youwouldn’t even be able to pick it up.The planets orbit the Sun as a result of itsgravity.
The Sun and Earth both have mass so theyboth have gravity.As a result of the force of gravity, the twobodies are being pulled together and wouldeventually crash except:The Earth has inertia, it’s trying to go in astraight line, but the Sun’s gravity keepspulling on it, keeping Earth (and the otherplanets) in orbit.The two forces the Earth’s inertia and gravitybalance one another; as a result the Earthremains in an orbit around the Sun.
Sun Gravitational pull of the SunEarth Resulting path Earth’s of the Earth inertia
The Sun’s gravity pulls its mass (mainlyhydrogen and helium) into an almost perfectsphere.At the the center of this sphere (the core)of the Sun, the heat and pressure are sostrong that fusion reactions in whichhydrogen nuclei changes into heliumnuclei occur.When nuclear fusion takes place insidethe Sun, tremendous amounts of energyare released.
This energy is made up of many kinds ofradiation. These different forms of radiationmake up what is called the electromagneticspectrum.The electromagnetic spectrum includesgamma rays, X-rays, ultraviolent rays, visiblelight rays, infrared rays, microwaves (radar)waves, FM radio waves, TV rays and AM radiowaves.
Electromagnetic Spectrum of Light from the Sun http://www.dnr.sc.gov
When the solar wind reaches the earththe magnetic field of the earth willsometimes trap these electrons andprotons and pull them into the earthsatmosphere.Atoms in the earths atmosphere acceptenergy from these high energy particlesand then release that energy in the formof colored light.
The Sun is one of the billions of stars thatmake up the spiral galaxy called the MilkyWay.
The distance from the Sun to various otherobjects is shown in this clip: http://www.valdosta.edu/~cbarnbau/astro_de mos/frameset_moon.html
The Sun has been “shining” for about 4.6billion years and has enough fuel to go onfor another five billion years or so.At the end of its life, the Sun will start tofuse helium into heavier elements andbegin to swell up, ultimately expandingout in the Solar System large that it willswallow up all the planets including theEarth.
After a billion years as a red giant, it willcollapse into a while dwarf.