History of Sun in Timeline

The Sun, the star at the center of our Solar System, is a massive sphere of hot plasma. It generates energy through nuclear fusion in its core, emitting primarily visible light and infrared radiation, with a smaller portion as ultraviolet. As the most crucial energy source for life on Earth, the Sun has been revered across various cultures and has been a focus of astronomical study since ancient times. Its properties and behavior continue to be a central topic in astrophysics.

1904: Rutherford suggested radioactive decay as the Sun's heat source

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

1920: Eddington proposed nuclear fusion in the Sun

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.

1925: Payne confirmed the preponderance of hydrogen in the Sun

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

1957: Burbidge, Burbidge, Fowler and Hoyle showed that most 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 synthesised by nuclear reactions inside stars, some like the Sun.

1959: Launch of Pioneer 6

In 1959 NASA launched Pioneer 6, the first satellite designed for long term observation of the Sun from interplanetary space.

1968: Launch of Pioneer 9

In 1968 NASA launched Pioneer 9, part of the Pioneer program and designed for long term observation of the Sun from interplanetary space.

1973: Launch of Skylab with Apollo Telescope Mount

In 1973, NASA launched the Skylab space station, which included a solar observatory module called the Apollo Telescope Mount.

1980: Launch of the Solar Maximum Mission

In 1980, NASA launched the Solar Maximum Mission probes to observe gamma rays, X-rays, and UV radiation from solar flares.

May 1983: Pioneer 9 stopped transmitting data

Pioneer 9, launched between 1959 and 1968, operated for a particularly long time, transmitting data until May 1983.

1984: Repair of Solar Maximum Mission by Space Shuttle Challenger

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

June 1989: Solar Maximum Mission re-entered Earth's atmosphere

In June 1989, the Solar Maximum Mission, launched in 1980, re-entered Earth's atmosphere after acquiring thousands of images of the solar corona.

1990: Launch of the Ulysses probe

In 1990, the Ulysses probe was launched to study the Sun's polar regions. The probe first travelled to Jupiter, to "slingshot" into an orbit that would take it far above the plane of the ecliptic.

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

2001: Yohkoh went into standby mode

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

2001: Discovery of neutrino oscillation resolved neutrino discrepancy

In 2001, the discovery of neutrino oscillation resolved the discrepancy in neutrino measurements: the Sun emits the predicted number of electron neutrinos, but detectors missed 2/3 of them due to flavor changes.

December 2004: Voyager 1 passed through a shock front

In December 2004, the Voyager 1 probe passed through a shock front thought to be part of the heliopause.

2005: Yohkoh destroyed by atmospheric re-entry

In 2005, Yohkoh (Sunbeam) satellite was destroyed by atmospheric re-entry.

2008: Prediction of Earth's engulfment by the Sun

According to a 2008 article, Earth's orbit will initially expand 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 2012: Voyager 1 entered the interstellar medium

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

2016: Discovery of Proxima Centauri b

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

April 2021: Parker Solar Probe penetrated the Alfvén surface

On 28 April 2021, NASA's Parker Solar Probe encountered specific magnetic and particle conditions at 18.8 solar radii, indicating penetration of the Alfvén surface, and passed into and out of the corona several times, confirming predictions that the Alfvén critical surface has spikes and valleys.