The Sun is the star at the center of the Solar System

The Sun is the star at the center of the Solar System. It is a nearly perfect sphere of hot plasma,^[15][16] with internal convective motion that generates a magnetic field via a dynamo process.^[17] It is by far the most important source of energy for life on Earth. Its diameter is about 1.39 million kilometers (864,000 miles), or 109 times that of Earth, and its mass is about 330,000 times that of Earth. It accounts for about 99.86% of the total mass of the Solar System.^[18] Roughly three quarters of the Sun's mass consists of hydrogen(~73%); the rest is mostly helium (~25%), with much smaller quantities of heavier elements, including oxygen, carbon, neon, and iron.^[19]

Sun

Sun with sunspots and limb darkening as seen in visible light with solar filter.
False-color photo of the Sun as seen in ultraviolet light (wavelength of 30.4 nm)
Observation data
Mean distance from Earth	1 au ≈ 1.496×108 km[1] 8 min 19 s at light speed
Visual brightness (V)	−26.74[2]
Absolute magnitude	4.83[2]
Spectral classification	G2V[3]
Metallicity	Z = 0.0122[4]
Angular size	31.6–32.7 minutes of arc[5]
Adjectives	Solar
Orbital characteristics
Mean distance from Milky Way core	≈ 2.7×1017 km 27,200 light-years
Galactic period	(2.25–2.50)×108 yr
Velocity	≈ 220 km/s (orbit around the center of the Milky Way) ≈ 20 km/s (relative to average velocity of other stars in stellar neighborhood) ≈ 370 km/s[6] (relative to the cosmic microwave background)
Physical characteristics
Equatorial radius	695,700 km,[7] 696,342 km[8] 109 × Earth[9]
Equatorial circumference	4.379×106 km[9] 109 × Earth[9]
Flattening	9×10−6
Surface area	6.09×1012 km2[9] 12,000 × Earth[9]
Volume	1.41×1018 km3[9] 1,300,000 × Earth
Mass	1.9885×1030 kg[2] 333,000 × Earth[2]
Average density	1.408 g/cm3[2][9][10] 0.255 × Earth[2][9]
Center density(modeled)	162.2 g/cm3[2] 12.4 × Earth
Equatorial surface gravity	274 m/s2[2] 28 × Earth[9]
Moment of inertia factor	0.070[2] (estimate)
Escape velocity (from the surface)	617.7 km/s[9] 55 × Earth[9]
Temperature	Center (modeled): 1.57×107 K[2] Photosphere (effective): 5,778 K[2] Corona: ≈ 5×106 K
Luminosity (Lsol)	3.828×1026 W[2] ≈ 3.75×1028 lm ≈ 98 lm/W efficacy
Color (B-V)	0.63
Mean radiance (Isol)	2.009×107 W·m−2·sr−1
Age	≈ 4.6 billion years[11][12]
Rotation characteristics
Obliquity	7.25°[2] (to the ecliptic) 67.23° (to the galactic plane)
Right ascension of North pole[13]	286.13° 19 h 4 min 30 s
Declination of North pole	+63.87° 63° 52' North
Sidereal rotation period (at equator)	25.05 d[2]
(at 16° latitude)	25.38 d[2] 25 d 9 h 7 min 12 s[13]
(at poles)	34.4 d[2]
Rotation velocity (at equator)	7.189×103 km/h[9]
Photospheric composition (by mass)
Hydrogen	73.46%[14]
Helium	24.85%
Oxygen	0.77%
Carbon	0.29%
Iron	0.16%
Neon	0.12%
Nitrogen	0.09%
Silicon	0.07%
Magnesium	0.05%
Sulfur	0.04%

What is world wide web [www] you must be known

WWW" and "The Web" redirect here. For other uses of WWW, see WWW (disambiguation). For other uses of web, see Web (disambiguation).

For the first web software, see WorldWideWeb.

Not to be confused with the Internet.

A web page can be displayed using a web browser. Web browsers often highlight and underline hypertext links and web pages can contain images.

A global map of the web index for countries in 2014

The World Wide Web (WWW), commonly known as the Web, is an information systemwhere documents and other web resourcesare identified by Uniform Resource Locators(URLs, such as https://www.example.com/), which may be interlinked by hypertext, and are accessible over the Internet.^[1] The resources of the WWW may be accessed by users by a software application called a web browser.

English scientist Tim Berners-Lee invented the World Wide Web in 1989. He wrote the first web browser in 1990 while employed at CERNnear Geneva, Switzerland.^[2][3] The browser was released outside CERN in 1991, first to other research institutions starting in January 1991 and then to the general public in August 1991. The World Wide Web has been central to the development of the Information Ageand is the primary tool billions of people use to interact on the Internet.^[4][5][6]

Air pollution[Important news]

iStock

What Is Air Pollution?

Air pollution refers to the release of pollutants into the air that are detrimental to human health and the planet as a whole.

The Clean Air Act authorizes the U.S. Environmental Protection Agency (EPA) to protect public health by regulating the emissions of these harmful air pollutants. The NRDC has been a leading authority on this law since it was established in 1970.

What Causes Air Pollution?

“Most air pollution comes from energy use and production,” says John Walke, director of the Clean Air Project, part of the Climate and Clean Air program at NRDC. “Burning fossil fuels releases gases and chemicals into the air.” And in an especially destructive feedback loop, air pollution not only contributes to climate change but is also exacerbated by it. “Air pollution in the form of carbon dioxide and methane raises the earth’s temperature,” Walke says. “Another type of air pollution is then worsened by that increased heat: Smog forms when the weather is warmer and there’s more ultraviolet radiation.” Climate change also increases the production of allergenic air pollutants including mold (thanks to damp conditions caused by extreme weather and increased flooding) and pollen (due to a longer pollen season and more pollen production).

Effects of Air Pollution

“While we’ve made progress over the last 40-plus years improving air quality in the U.S. thanks to the Clean Air Act, climate change will make it harder in the future to meet pollution standards, which are designed to protect health,” says Kim Knowlton, senior scientist and deputy director of the NRDC Science Center.

Blogger stories by Beth kephart[cool stories]

Blogger Stories: Beth Kephart

Some artists paint with colors, some with movement some with notes. Beth Kephart paints with words. I virtually metBeth through our mutual friend, Nettie Hartsock, and was immediately captivated by how she uses words. Her recent book, Undercover was written for the youth market; however, this story of a young teenage girl is must read for young and old. For Beth blogging is a treasure hunt for the imagination where she combines heart, soul and insights on a quest to write the illusive perfect post. 

Blogger Story Teller: Beth Kephart, Beth Kephart Books

Writing indulges the myth of continuity.  Photographs suggest the significance of the single instant.  Ever since a fourth-grade teacher helped me turn a Quaker Oats container into a pinhole camera, I’ve been chasing photographs, and I fell hard for words (the sound of them, their shape) at about the same time. I’ve been caught in both lures ever since. 

Blogging lets me play with the mix. When I sit down to post, I’m thinking about triggers. I’m thinking about something I might have heard on a train or something the wind might have blown my way or something I’ve been battling with. Then I’m thinking about the iconography—the way a photo might be used to create an amplifying metaphor. Between the story that I write and the photo that accompanies it, there’s tension, and often that tension—the story not spoken, the bridge not built—is the place where the next blog begins, the thing I start battling with.

I’m writing, and I’m thinking about who might be listening. I’m writing, and I’m listening back.  Blogging isn’t like writing a book, and it isn’t like writing a letter. It’s something new, a backwards cascade, and I love the challenge of it. I haven’t yet blogged a perfect blog, but I’m aching toward it. 

One of the things I’m careful of is providing a cohering blog experience, despite the fact that I don’t live anything close to a coherent-seeming life.  I split my time between running a communications business (we tell stories at Fusion — work with clients to develop books and brochures and web pages that celebrate, commemorate, explain), writing books, teaching writing workshops, and being a mother and wife.  My most recent books have all been exercises in the very new, for me. 

FLOW: THE AUTOBIOGRAPHY OF THE SCHUYLKILL RIVER, tells the story of a river in her own words.

 UNDERCOVER, my first novel for young adults, celebrates poetry and explores identity through a female Cyrano character.

ZENOBIA: THE CURIOUS BOOK OF BUSINESS, due out in January and co-authored with the CEO of a $14 billion pharma company, takes an Alice in Wonderlandesque look at the role of the imagination in corporate America.

Global warming

This page is about the current warming of the Earth's climate system. "Climate change" can also refer to climate trends at any point in Earth's history. For other uses see Global warming (disambiguation).

Global mean surface-temperature change from 1880 to 2018, relative to the 1951–1980 mean. The 1951–1980 mean is 14.19 °C (57.54 °F).^{[1][attribution needed]} The black line is the global annual mean, and the red line is the five-year local regression line. The blue uncertainty bars show a 95% confidence interval.

Average global temperatures from 2014 to 2018 compared to a baseline average from 1951 to 1980, according to NASA's Goddard Institute for Space Studies.

Global warming is a long-term rise in the average temperature of the Earth's climate system, an aspect of climate change shown by temperature measurements and by multiple effects of the warming.^[2][3] Though earlier geological periods also experienced episodes of warming,^[4] the term commonly refers to the observed and continuing increase in average air and ocean temperatures since 1900 caused mainly by emissions of greenhouse gases in the modern industrial economy.^[5] In the modern context the terms global warming and climate changeare commonly used interchangeably,^[6] but climate change includes both global warmingand its effects, such as changes to precipitation and impacts that differ by region.^[7][8] Many of the observed changes in climate since the 1950s are unprecedented in the instrumental temperature record, and in historical and paleoclimate proxy records of climate change over thousands to millions of years.^[2]