Sun

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Sun : (1) the luminous celestial body around which the earth and other planets revolve, from which they receive heat and light, which is composed mainly of hydrogen and helium, and which has a mean distance from earth of about 93,000,000 miles (150,000,000 kilometers), a linear diameter of 864,000 miles (1,390,000 kilometers), and a mass 332,000 times greater than earth (2) a celestial body like the Sun — Merriam-Webster See also OneLook

Thesaurus

Roget’s II (Thesaurus.com), Merriam-Webster Thesaurus, Visuwords

Encyclopedia

The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy mainly as visible light, ultraviolet, and infrared radiation. It is the most important source of energy for life on Earth. The Sun’s diameter is about 1.39 million kilometers (864,000 miles), or 109 times that of Earth. Its mass is about 330,000 times that of Earth, comprising about 99.86% of the total mass of the Solar System. 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.

The Sun is a G-type main-sequence star (G2V). As such, it is informally, and not completely accurately, referred to as a yellow dwarf (its light is closer to white than yellow). It formed approximately 4.6 billion years ago from the gravitational collapse of matter within a region of a large molecular cloud. Most of this matter gathered in the center, whereas the rest flattened into an orbiting disk that became the Solar System. The central mass became so hot and dense that it eventually initiated nuclear fusion in its core. It is thought that almost all stars form by this process. — Wikipedia

Sun (Encyclopædia Britannica)

Sun (COSMOS: The SAO Encyclopedia of Astronomy)

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Adventures

Explore related posts on Cosma …

Touch the Sun - Remember how Icarus wanted to touch the Sun, but met his demise instead? Well, scientists at NASA wanted to touch the Sun too, but unlike Icarus, they succeeded! Better yet, they are beginning to share what they learned by doing it! Before we get into all of that, let’s go back and start at the … Continue reading Touch the Sun
Umbraphiles - umbraphile : One who loves eclipses, often travelling to see them. You’ve probably heard about the April 8th solar eclipse (Wikipedia), and if you live near the path of totality, then you’ve probably also seen news stories like this one. Party in the Path of Totality at These Solar Eclipse Getaways Across New England (Kristi … Continue reading Umbraphiles

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Inspiration

Note: These are 360° Videos — press and hold to explore them!

NASA (YouTube Channel)
NASA (Official Website)

The Sun (Astrum, YouTube Playlist)

Talks about the Sun (TED: Ideas Worth Spreading)
Articles about the Sun (Big Think)

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Innovation

Science

Heliophysics means “physics of the Sun” (the prefix “helio”, from Attic Greek h?lios, means Sun), and appears to have been used only in that sense until quite recently. In the early times, heliophysics was concerned principally with the superficial layers of the star, and was synonymous with what is now more commonly called “solar physics”. Usage was extended explicitly in 1981 to its literal meaning, denoting the physics of the entire Sun: from center to corona, and has been used in that sense since. — Wikipedia

Heliophysics (NASA Goddard, YouTube Playlist)
NASA Heliophysics (Official Website)

Science of Heliophysics (HELIO Heliophysics Integrated Observatory)

EZ Science (NASA, YouTube Channel)
EZ Science (EZ Science, Official Website)

Sun (NASA Science)

The Sun Videos (ViewSpace, Space Telescope Science Institute)

The Sun, Our Solar System’s Star (Planetary Society)
Our Sun (Lunar & Planetary Institute)

Sun (Eric Weisstein’s World of Astronomy, Wolfram Research)
Solar Atmosphere (Eric Weisstein’s World of Astronomy, Wolfram Research)

Sun (Wolfram Alpha)
Space Weather (Wolfram Alpha)

Technology

Earth resides in the vast atmosphere of a star – and that star creates a dynamic and complex space environment that can sometimes interfere with space technology, communications and navigation systems, and utility grids. The Living With A Star (LWS) program targets specific aspects of the Sun-Earth system that affect life and society. LWS provides a predictive understanding of the Sun-Earth system, linkages among the interconnected systems, and, specifically, space weather conditions at Earth and the interplanetary medium. — LNASA Heliophysics

Living With a Star Program (NASA Heliophysics)

Solar Dynamics Observatory Launched in 2010, the SDO seeks to understand the Sun’s influence on Earth and near Earth space by simultaneously studying the solar atmosphere on small scales of space and time and in many wavelengths. — Living With a Star Program (NASA Heliophysics)

NASA Goddard (YouTube Channel)
NASA Goddard Space Flight Center (Official Website)

The Solar Dynamics Observatory (NASA Goddard, YouTube Playlist)

NASA’s Solar Dynamics Observatory (Official Website)
Solar Dynamics Observatory (Wikipedia)

Parker Solar Probe Launched in 2018, Parker is unlocking the mysteries of the Sun’s atmosphere. Parker Solar Probe will fly through the solar corona 24 times, gradually lowering its orbit closer to the Sun using Venus’ gravity during seven flybys over its seven-year mission — Living With a Star Program (NASA Heliophysics)

NASA Goddard (YouTube Channel)
NASA Goddard Space Flight Center (Official Website)

Parker Solar Probe (NASA Video, YouTube Playlist)

NASA’s Parker Solar Probe (Offical Website)
Parker Solar Probe (Wikipedia)

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Preservation

History

NASA Goddard, YouTube Channel)
NASA Goddard Space Flight Center (Official Website)

Earth, Planetary, and Solar Science History (NASA’s History Office)

Missions to the Sun (NASA Science)

History of Observation of the Sun (Encyclopædia Britannica)
Sun (World History Encyclopedia)

Library

DDC: 523.7 The Sun (Library Thing)
Subject: Sun (Library Thing)

Subject: Sun (Open Library)

LCC: QB 520 The Sun (UPenn Online Books)

LCC: QB 520 The Sun (Library of Congress)

Subject: Sun (WorldCat)

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Participation

Education

NASA Space Place (YouTube Channel)
NASA Space Place (Official Website)

Why Does the Sun Burn Us? (Space Place, NASA)

NASA Goddard (YouTube Channel)
NASA Goddard Space Flight Center (Official Website)

The Sun – Level 1 (StarChild, Goddard Space Flight Center, NASA)
The Sun – Level 2 (StarChild, Goddard Space Flight Center, NASA)

Sun (Imagine the Universe, NASA Goddard Space Flight Center)

The Sun and Its Influence on Earth (Crash Course Kids Space Science, YouTube Playlist)

The Sun (Science Trek)
Sun (Cosmos4Kids)

The Sun (Crash Course Astronomy, YouTube Video)

The Life-Giving Sun (Introduction to Astronomy, Wolfgang H. Berger, UC San Diego)

The Sun (Astronomy Center, ComPADRE)

MERLOT: Multimedia Educational Resource for Learning and Online Teaching
OER Commons: Open Educational Resources

Community

Organization

International Astronomical Union Division E – Sun and Heliosphere
International Astronomical Union Division G – Stars and Stellar Physics

Solar Section (British Astronomical Association)

News

Heliophysics (NASA Science)
Sun (Nova Research Highlights, American Astronomical Society)
Heliophysics (EurekaAlert, AAAS)
Observing the Sun (Astronomy Magazine)
Heliophysics (JSTOR)
Sun (Science Daily)
Heliophysics (Phys.org)

Recent News from Phys.org …

The threat of light pollution puts the world's...
on April 26, 2026 at 3:40 pm
It takes a moment for the eyes to adjust. A faint spark appears in the darkness; then another, brighter one. Soon, stars, planets and entire constellations emerge. Before long, a whole galaxy stretches across the sky, visible to the naked eye.
Volunteers discover rare space weather events...
on April 17, 2026 at 5:20 pm
Our planet rests inside a magnetic cocoon filled with plasma—but it's not always peaceful and quiet. Activity from the sun can send waves through this space, and some of those disturbances can even reach Earth, affecting our power grid.
Virtual sunspots help AI find rare magnetic...
on April 14, 2026 at 10:10 pm
Research led by Southwest Research Institute (SwRI) has integrated three types of machine learning models to generate solar magnetic patches with physical properties and used those as a query to find matching patches in real observations. This elevates generative artificial intelligence (AI) from a means to produce artificial data to a novel tool for scientific data interrogation, supporting applicability beyond the heliophysics domain. The paper is published in The Astrophysical Journal […]
Student research on coronal holes improves space...
on April 8, 2026 at 7:00 pm
Fast solar winds originating from the sun can have direct impacts on Earth—disrupting systems like GPS, aviation, electrical grids, and satellite and radio communications. A new paper by New Mexico State University astronomy graduate student Khagendra Katuwal examines the connection between coronal holes and solar wind streams, helping improve our understanding of how the sun's magnetic structure influences space weather.
Physicists trace the sun's magnetic engine,...
on March 17, 2026 at 8:00 pm
Every eleven years, the sun's magnetic field flips. Sunspots—dark, cooler regions on the sun's surface that mark intense magnetic activity and often trigger solar eruptions—appear at mid-latitudes and migrate toward the star's equator in a butterfly-shape pattern before fading as the cycle resets. While this spectacle on the star's surface has long been visible to astronomers, where this powerful cycle begins inside the star has remained hidden until now.