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Sun, star around which Earth and the other components of the solar system revolve. It is the dominant body of the system, constituting more than 99 percent of its entire mass.

Sun-Earth Day is a celebration established in 2000 by NASA and ESA. The purpose of the holiday is to popularize the knowledge about the Sun, and the way it influences life on the Earth.
[edit] See also ...

Sun, the solar system's only star
Stars are born. They take shape. They go through a turbulent adolescence, and then they live out their lives in a predictable pattern. Some have companions to provide for. Others rapidly decline and die. In some ways, stars are just like people.

Sun and planets formed from different ingredients
Posted: 28 June 2011 ...

sun at HighBeam Research
sun on Wikipedia
sun. Wikimedia Commons (Public Domain) ...

The ~ in Mythology
Creation is often linked to a combination of the ~ (Male) and Moon (Goddess) - representing duality in physical reality.

~ Information
Enchanted Learning Search
First search engine with spelling correction and pictures! ...

The ~'s atmosphere consists of the chromosphere, corona, and photosphere. The photosphere is the bright visible surface of the ~, with a surface temperature of 5,800 K. The chromosphere consists of the bright gases just above the photosphere of the ~ and is 10,000-15,000 km thick.

The ~ in the He II emission line.
The ~ is the Earth's dominant source light (and thus heat) and the star about which all of the planets of the solar system orbit. The ~ has mass 1.989 1030 kg and a radius of ~700,000 km.

The ~
The sun has guided human life for all of history, and it has also been the facilitator of life on our planet. It is the most obvious object in the sky, but in the grand scheme of things, the sun is an average star with no special significance.

The ~ is a star at the center of our solar system. Our ~ is a medium-sized yellow star that is 93,026,700 miles (149,680,000 km) from Earth. Its diameter is 865,121 miles (1,391,980 km).

Our ~ is gorgeous, and dangerous, and amazing. These pictures and videos are more than just beautiful; they are telling us about the mechanisms and processes occurring both on the surface and inside our nearest star. Given the impact this can have on Earth, the more we know, the better.

Wikipedia, the free encyclopedia - Cite This Source
The ~ (Sol) is the star at the center of the Solar System. The Earth and other matter (including other planets, asteroids, meteoroids, comets and dust) orbit the ~, which by itself accounts for about 99.8% of the solar system's mass.

~ Watching Satellite SOHO Regains Ability
Solar and Heliospheric Observatory (SOHO), the ~-watching satellite, has regained most of its capability after having been shut down partially in June-July 2003 when its high-gain antenna froze up reducing its ability to transmit data to Earth.

~ City Palm Desert Astronomy Club
Please contact this organization for information on their astronomy viewing schedules, telescope availability, membership, and public programs.
~ City Palm Desert Astronomy Club ...

"~ Observer's Guide" by Pam Spence,159 pp., Firefly Books, 2004. A concise and readable overview. Questions from Users: The color and temperature of stars and of the ~
*** Questions about the Solar Corona:
(1) Why don't its particles separate by weight?

The ~'s Surface
The deepest layer of the ~ you can see is the photosphere. The word ``photosphere'' means ``light sphere''. It is called the ``surface'' of the ~ because at the top of it, the photons are finally able to escape to space. The photosphere is about 500 kilometers thick.

The ~
Our ~ is a yellow dwarf star. Its official designation is as a G V star. Stars in the this classification have a surface temperatures between 5,300 and 6,000 K and fuse hydrogen into helium to generate their light. They generally last for 10 billion years.

Our ~'s Lost Sibling
By Brian Ventrudo
Like most stars in the Milky Way, our ~ was born in a cluster of hundreds of new stars in a cloud of glowing gas and dust like the Orion Nebula, then settled down with its siblings in an open star cluster like the Pleiades.

The ~
Many ancient peoples worshiped the ~ as a god. They thought a solar eclipse meant the god was angry with them. They believed the ~ god's anger could only be calmed with prayer and sacrifice.

The ~ in Time
home page
...is a program designed to integrate science and social studies curricula through a study of Solar Science and Archaeoastronomy.

The ~
Our ~ is a normal main-sequence G2 star, one of more than 100 billion stars in our galaxy. diameter: 1,390,000 km. mass: 1.989e30 kg temperature: 5800 K (surface) 15,600,000 K (core) ...

The Sun: An Introduction to the Stars
In this course, Astronomy 124, we will be learning about the contents of the universe, from the relatively small scales of a single star system up to the largest distances known, namely the entire visible universe.

The star at the center of our solar system. An average star in terms of size and mass, the ~ is a yellow dwarf of spectral type G2. It is about 5 billion years old, contains 2 * 1030 kilograms of material, and has a diameter more than 100 times that of Earth.
~spot ...

~ spots come and go on a regular basis. At times there are very few if any sun spots. Other times there are far more. They generally increase in intensity and then decrease over a period of 11 years. This 11 year cycle is known as the Saros Cycle.
Solar Flares ...

~ Headlines
things you should know about your hamster's cage
Everyone has a dead bird story ...

The ~. Courtesy of SOHO (ESA & NASA)The ~ is steadily converting the hydrogen in its core into helium. As the available fuel runs out the energy output declines. Outward pressure declines too and so the core of the ~ shrinks.

The ~ is one of the only two objects which can be seen year round by people around the world. The other is, of course, the Moon. The ~ is, however, the only object in the sky which can be dangerous to view.

The ~ and its entourage of planets travel in the general direction of Vega (away from Sirius), orbiting the center of the Milky Way at some 140 to 150 miles per second. Even at this breakneck speed, it takes something like 225 million years for the ~ to complete one revolution around the Galaxy.

The ~ at wavelengths from x-ray to radio.
Views of the Solar System
Bill Arnett's Solar Tour
Space Weather
A solar virtual tour.
An excellent pictorial introduction to the sun.
Solar Heliospheric Observatory (SOHO). Solar Image Gallery.

The ~ also has an influence on the tides, but since it is further away, it doesn't pull as strongly. However, when both the Moon and the ~ are pulling along the same axis, the tides are highest.

"The ~ strings these worlds - the earth, the planets, the atmosphere - to himself on a thread." ...

How did the ~'s family of planets and minor bodies originate?
How did the solar system evolve to its current diverse state?
How did life begin and evolve on Earth, and has it evolved elsewhere in the Solar System?

A model of the ~ shows its nuclear fusing core (where hydrogen is turned into helium by the conversion of mass into energy), an envelope where energy is transferred by radiation, and an outer layer where convection (the rising of hot gases, falling of cool gases) rules.

Observing Where the ~ Sets
Grade Level: 3-5
Lesson Time: Less Than 30 Minutes
Body: ~, Earth
Mission: Earth Science Missions (Earth), Heliophysics Missions (~) ...

Set it on a flat surface and rotate the base of the fixture so that the North Pole is farthest away from an imaginary light source (the ~). This simulates winter in the northern hemisphere; summer in the southern hemisphere. For illustrative purposes, let's consider Alaska.

Thus, in the Copernican model the ~ was at the center, but the planets still executed uniform circular motion about it. As we shall see later, the orbits of the planets are not circles, they are actually ellipses.

Analysis of data from GONG and other sources shows that current theories about the structure of the ~ need to be expanded.

The ~ will appear directly opposite it on the sky, so subtract 12h from the right ascension (or add 12h, as the case may be), and change the sign of the declination. That puts the ~ at 5h 57.8m, -4 42', in the constellation Orion as seen from Barnard's Star.

Welcome to the Tour of Our ~! The following pages will tell you about how scientists are studying our ~ this very minute.
There are about eight main pages to this tour with lots of hyperlinks to more technical information. Be sure to watch several of our solar movies - they're really cool!! ...

~ and Planets
The following table compares major features of the ~ and planets, and relates many planetary characteristics to Earth's own:
(AU) ...

~ redirects here. For information on Earth's ~, see Sol. You may be searching for the actress Star.

~ Liang was an emperor of Eastern Wu during the Three Kingdoms period. He was the founding emperor ~ Quan's youngest son and heir.

~: The ~ is a star and the biggest object in the Solar System, it burns brightly in the center as planets and other objects orbit around it. It has a diameter around 110 times bigger than the Earth’s and is located around 150 million kilometres (93 million miles) away.

~: One of the 100 billion stars in our galaxy. 1,390,000 km diameter. Temperature at the core: 15,600,000 K. Temperature at the surface: 5800 K.

~: The star associated with Earth's solar system. The ~ weighs about 2x1030 kilograms, and is about 1.4x109 meters in diameter.
Supergiant: Very luminous star 10-1000 time more massive than the ~.

~ synchronous orbit -- A spacecraft orbit that precesses, wherein the location of periapsis changes with respect to the planet's surface so as to keep the periapsis location near the same local time on the planet each orbit. See walking orbit.

The star at the centre of our solar system, providing the light and heat required for life on Earth.
A device used to determine the time of day by observing shadows cast by a gnomon.

~ - Our parent star. The structure of ~'s interior is the result of the hydrostatic equilibrium between gravity and the pressure of the gas. The interior consists of three shells: the core, radiative region, and convective region.

(a) The star that Earth orbits. The ~ is a yellow main-sequence star that is spectral type G2, shines with apparent magnitude -26.74, and has an absolute magnitude of +4.83. The ~ is 4.6 billion years old.

~, Mercury, Venus, Earth, Moon, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto, Quaoar, Asteroids, Comets, Sedna ...

The ~ Is Moved To The Center
They explained this by assuming the planets and stars (as well as the Moon and ~) were fixed on large, concentric, invisible, rotating spheres with the Earth at their center.

The ~
08.18.09 - Read about Earth's ~, and learn a song, too!
What Is NASA?

THE ~ IN X-rays
What sort of radiation is emitted by a gas of 1,000,000 K? Unlike the 5800 K photosphere, which emits most strongly in the visible part of the electromagnetic spectrum, the hotter coronal gas radiates at much higher frequencies"primarily in X-rays.

Mean ~. An imaginary ~ travelling at a speed equal to the average rate that the real ~ travels along the ecliptic.
Mean. The average of a series of values.
Megaparsec. One million parsecs, a distance equal to 3 260 000 light years.

and ∴ ~'s diameter = 1,390,000 km (or 1.39 - 109 m).
If a star is 20 parsecs away and has an apparent magnitude of +6, what is its absolute magnitude?

1) Why the ~ and Moon live in the sky Retold and Illustrated by Niki Daly $15.00 (hardcover) African Myth - This book was also found on the shelf of Barnes and Nobles ...

~, Moon & Planets - now!
Your browser does not support iframes or is configured not to display them. You may wish to enable iframes in your browser's preferences, if that option is available to you, so that this content may be displayed.
telescope-net ...

~ The star at the center of our solar system. It is made mostly of hydrogen and helium with traces of heavier elements. This image of the ~ is courtesy of SOHO/EIT.
More about the ~...

~-centered; using the ~ rather than the earth as the point to which we refer. A heliocentric measurement, for example, omits the effect of the Doppler shift caused by the earth's orbital motion.
helium - (n.)
atom consisting of two protons and two electrons.

A ~ like star is dying. It becomes
? a brown dwarf.
? a yellow giant;
? a red super giant
? a red giant.

No ~ tan lotion required
Pluto is situated so far out in the depths of the solar system that if you were to stand on its surface the ~ would just look like a bright star.
Size matters ...

The ~ shining through the Stonehenge monument. ~ rise on the summer solstice was the most important time the ~ would shine through the monument.
Click on image for full size
Windows to the Universe original image ...

The ~ passes this constellation from late July to early August. In former times the ~ used to lie in this constellation when it reaches the its point farthest north - the time of the summer solstice.

The ~ and Earth pass through Saturn's ring plane on August 10th and September 4th, 2009. However, unlike the Saturn ring plane crossing of 1995, the 2009 events will occur when Saturn, viewed from Earth, is close to the ~.

The ~ is in Pisces from March 13 to April 19, and it crosses the ecliptic on March 21, which marks the vernal Equinox, the first day of autumn in the southern hemisphere. This used to be called the first point in Aries, but precession has now moved it into Pisces.

The ~, a spectral class G2 star that contains 99.86% of system's mass.
The planets of the solar system are those nine bodies traditionally labelled as such; Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto.

The ~ is in the galactic disk, about half-way from the galactic center to the outer edge of the disk. All of the stars we see in the sky are part of this disk. The stars that make that band up are close to us, because dust in the disk eventually blocks our view. At its distance of 7.

The ~ is a star and a strong source of radio emission. Most ordinary stars are expected to emit radio waves since they are thermal sources. However, the majority of the radio emission from stars is undetectable since they are far away and the signals are too faint.

The ~ as seen through my 10-inch Meade Schmidt Cassegrain telescope in Orlando, Florida on 3/14/89. This image was captured on Kodak Ektachrome 100 color slide film with a Thousand Oaks full-aperture glass solar filter.

The ~ and nearby disk stars share a common orbital motion about the galactic center, but in addition each has a small random velocity, reflecting the fact that their orbits are not perfect circles.

Our ~ is heading away from Columba as fast as it can go. Columba contains the "solar antapex" which is the opposite of the solar apex, which is the direction the ~ is headed. Right now, we seem to be journeying toward the constellation Hercules.

The ~, or any star for that matter, "shines" or "burns" due to a process of thermonuclear fusion, not due to a chemical reaction like the oxygen-driven fires on Earth.

The ~ is at the center of the universe and everything revolves around that. Was first proposed by Copernicus.
The study of the interior of the ~ by the analysis of its modes of vibration.

The ~'s path across the sky. The Moon and the planets follow this path closely, since their orbital planes are nearly aligned with Earth's orbital plane. The ecliptic is tilted 23.5 degrees from the celestial equator.
effective temperature ...

The ~'s disk and the separation from the comet are shown to scale, with north at the top of the image and west to the right. Keep in mind that ISON will be very close to the ~ (1.5 on average, around three times the apparent diameter of the ~).

Of the ~.
Solar Nebula
The large cloud of gas from which the ~ and planets were formed 4,600 million years ago.

If the ~ were replaced by Betelgeuse, the surface of the star might stretch out beyond the asteroid belt. The planets out to the orbit of Mars would be engulfed by the star.

The ~ and moon both exert gravitational pull on the earth. This pull has a definite affect on the earth's rotation, because the earth is not perfectly spherical. The earth bulges at the equator.

In the ~ convection is also an important process. Convection becomes important whenever the opacity goes up and the rate of radiative diffusion becomes less. Then heat builds up and the boiling begins. Radiative diffusion is most important in the inner 80% of the ~, convection in the outer 20%.

One of the ~'s outer layers, visible for a few minutes as a spectacular halo during during a total eclipse of the ~.
A reddish-colored layer in the solar atmosphere, just above the photosphere.

Midnight ~
The ~ when visible at midnight, which happens only in summer north of the Arctic Circle or south of the Antarctic Circle.
Milky Way
Our own galaxy.

On nearing the ~, a comet may develop two tails. The solar wind of high-speed protons and electrons sweeps cometary ions in a direction away from the ~, producing a straight plasma or ion tail. A second tail consisting of dust particles about a micrometer in size may appear.

Kepler-20: A ~-like Star with Three Sub-Neptune Exoplanets and Two Earth-size Candidates
March 17, 2012 GAUTIER Th., CHARBONNEAU D., ROWE J., MARCY G., ISAACSON H., TORRES G. & 38 additional authors
ApJ., 749, 15
paper arxiv ...

active (of the ~; characterized by a high level activity in ~spots and flares and radio emissions)
stargaze (observe the stars)
go down; go under; set (disappear beyond the horizon) ...

The ~'s outer atmosphere, which has a high temperature and a low density.
coronal mass ejection
CME; an event in which billions of tons of gas from the ~'s corona is suddenly blasted into space at high speed.

Examining the ~:
Although we think of sunlight or starlight as white, it is really composed of a spectrum of colors - you can use a prism to break up sunlight into a rainbow (red, orange, yellow, green, blue, indigo and violet) - Isaac Newton was the first person to realize this.

corona: The ~'s outer atmosphere, with a temperature of greater than a million degrees, that gives rise to the solar wind.

A star like our ~ which is on the main sequence portion of the Hertzsprung Russell (HR) Diagram. This is a stable star burning hydrogen in the normal way which it will do for the vast majority of its life.

Heliocentric ~-centred.
Horizon Co-ordinates The system of celestial co-ordinates in which the observer's horizon is the reference plane and the north point is the reference direction. The positions are given in altitude and azimuth.

Next stars to the ~: alpha Cen, proxima Cen (~ 4,28 light years)
Double stars alpha Cen, beta Cen, gamma Cen, k Cen, D Cen
Variable stars mu Cen, T Cen, R Cen
Nebula IC 2944
Planetary nebula NGC 3918
Globular cluster omega Cen
Open star clusters NGC 5460, NGC 3766, NGC 5316, NGC 5617 ...

~ centered.
the point at which the solar wind meets the interstellar medium or solar wind from other stars.

The average mass of the ~ is about 2x1033 grams. Astronomers often express units for other objects in terms of solar units-- it makes the resulting numbers smaller and easier to deal with. Mach (NASA SP-7, 1965) = Mach number.

For stars, parallax is measured from the earth and the ~, and is called annual, heliocentric, or stellar parallax. Compare aberration. parallax error The error in measurement between two pairs of antenna caused by the fact that the center of the two baselines do not coincide.

One arc second is equal to about 725 km on the ~. Aurora A colorful, rapidly varying glow in the sky caused by the collision of charged particles in the magnetosphere with atoms in the Earth's upper atmosphere.

Example:the gravitational attraction of the ~ is a central force for the orbital motion of the planets.

See also: Apollo asteroids, Asteroid, Semimajor axis Comet A diffuse body of solid particles and gas, which orbits the ~. The orbit is usually highly elliptical or even parabolic.

If you had a basic understanding of how the solar system formed, that over the course of millions of years, atoms of hydrogen and helium along with dust and other gases, slowing coalesced under gravity to form the ~, using what was left over to make the planets, ...

In the case of solar-system objects such as comets and planets, one must ultimately account for perturbing gravitational effects of numerous other planets in the solar system (not merely the ~), and when such account is made, ...

See also: See also: What is the meaning of Astro, Earth, Planet, Solar, Star?

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