History of Sun in Timeline

The Sun is the Solar System's central star, a massive sphere of hot plasma powered by nuclear fusion. It radiates energy, primarily as visible light and infrared radiation, and is crucial for life on Earth. Revered across cultures, the Sun has been a focal point of astronomical study since ancient times.

1904: Rutherford Suggests Radioactive Decay as Heat Source

In 1904, Ernest Rutherford suggested that the Sun's output could be maintained by an internal source of heat, proposing radioactive decay as the energy source.

1920: Eddington Proposes Nuclear Fusion

In 1920, Sir Arthur Eddington proposed that the pressures and temperatures at the core of the Sun could produce a nuclear fusion reaction that merged hydrogen (protons) into helium nuclei, resulting in a production of energy from the net change in mass.

1925: Payne Confirms Preponderance of Hydrogen

In 1925, Cecilia Payne confirmed the preponderance of hydrogen in the Sun using the ionization theory developed by Meghnad Saha.

1957: Burbidge, Burbidge, Fowler and Hoyle show elements are synthesized by nuclear reactions inside stars

In 1957, Margaret Burbidge, Geoffrey Burbidge, William Fowler and Fred Hoyle showed that most of the elements in the universe have been synthesized by nuclear reactions inside stars, some like the Sun.

1959: Launch of Pioneer 6

In 1959, NASA's Pioneer 6, one of the first satellites designed for long term observation of the Sun from interplanetary space, was launched.

1968: Launch of Pioneer 9

In 1968, NASA's Pioneer 9, one of the first satellites designed for long term observation of the Sun from interplanetary space, was launched.

1973: Skylab Launched with Apollo Telescope Mount

In 1973, NASA launched Skylab space station, which included a solar observatory module called the Apollo Telescope Mount. Skylab made the first time-resolved observations of the solar transition region and of ultraviolet emissions from the solar corona.

1980: Launch of Solar Maximum Mission

In 1980, NASA launched the Solar Maximum Mission probes to observe gamma rays, X-rays and UV radiation from solar flares during a time of high solar activity.

May 1983: Pioneer 9 Transmits Data Until May 1983

Pioneer 9 operated for a particularly long time, transmitting data until May 1983.

1984: Space Shuttle Challenger Repairs Solar Maximum Mission

In 1984, Space Shuttle Challenger mission STS-41C retrieved the Solar Maximum Mission satellite and repaired its electronics before re-releasing it into orbit.

June 1989: Solar Maximum Mission Re-enters Earth's Atmosphere

In June 1989, the Solar Maximum Mission re-entered Earth's atmosphere after acquiring thousands of images of the solar corona.

1990: Launch of Ulysses Probe

The Ulysses probe was launched in 1990 to study the Sun's polar regions.

1991: Launch of Yohkoh Satellite

In 1991, Japan's Yohkoh (Sunbeam) satellite was launched to observe solar flares at X-ray wavelengths.

December 1995: Launch of SOHO

On December 2, 1995, the Solar and Heliospheric Observatory (SOHO), jointly built by the European Space Agency and NASA, was launched.

2001: Yohkoh Satellite Enters Standby Mode

In 2001, the Yohkoh satellite went into standby mode when an annular eclipse caused it to lose its lock on the Sun.

2001: Discovery of Neutrino Oscillation

In 2001, the discovery of neutrino oscillation resolved the discrepancy in the number of electron neutrinos produced in the Sun. The Sun emits the number of electron neutrinos predicted by the theory, but neutrino detectors were missing 2⁄3 of them because the neutrinos had changed flavor by the time they were detected.

December 2004: Voyager 1 Passes Through Shock Front

In December 2004, the Voyager 1 probe passed through a shock front believed to be part of the heliopause, marking a significant step in understanding the outer boundaries of the Sun's influence.

2005: Destruction of Yohkoh Satellite

In 2005, the Yohkoh satellite was destroyed by atmospheric re-entry.

2008: Article Predicts Earth's Engulfment by the Sun

According to a 2008 article, Earth's orbit will have initially expanded to at most 1.5 AU due to the Sun's loss of mass. However, Earth's orbit will then start shrinking due to tidal forces so that it is engulfed by the Sun during the tip of the red-giant branch phase 7.59 billion years from now.

August 25, 2012: Voyager 1 Enters Interstellar Medium

On August 25, 2012, Voyager 1 passed through the heliopause and entered the interstellar medium at approximately 122 astronomical units (18 Tm) from the Sun. This was indicated by a marked increase in cosmic ray collisions and a sharp drop in lower energy particles from the solar wind.

2016: Discovery of Proxima Centauri b

In 2016, a potentially habitable exoplanet was found to be orbiting Proxima Centauri, called Proxima Centauri b, the closest confirmed exoplanet to the Sun.

April 28, 2021: Parker Solar Probe Penetrates Alfvén Surface

On April 28, 2021, NASA's Parker Solar Probe encountered the specific magnetic and particle conditions at 18.8 solar radii, indicating that it penetrated the Alfvén surface, the boundary separating the corona from the solar wind. During the flyby, Parker Solar Probe passed into and out of the corona several times.