History of Asteroid in Timeline

An asteroid is a minor planet orbiting within the inner Solar System or co-orbital with Jupiter, larger than a meteoroid but not a planet or identified comet. Asteroids are atmosphere-less, rocky, metallic, or icy bodies, classified as C-type (carbonaceous), M-type (metallic), or S-type (silicaceous). Their sizes and shapes vary considerably, from small rubble piles to Ceres, a dwarf planet nearly 1000 km in diameter. An object is classified as a comet if it exhibits a coma (tail) when warmed by solar radiation, blurring the lines between the two.

1914: Asteroid Designation Using Greek Letters

In 1914, asteroid designations included year plus a Greek letter.

1918: Recognition of Main Belt Families

In 1918, Kiyotsugu Hirayama first recognized Main belt families and are often called Hirayama families in his honor.

1925: Establishment of Chronological Numbering System

In 1925, a simple chronological numbering system for asteroids was established.

1937: Close Approach of 69230 Hermes to Earth

In 1937, asteroid 69230 Hermes approached within 0.005 AU of Earth, leading astronomers to realize the potential for Earth impacts.

1967: Design of Project Icarus

In 1967, "Project Icarus" was designed as a contingency plan in case of collision with asteroid 1566 Icarus, using Saturn V rockets with nuclear warheads to deflect or destroy the asteroid.

1975: Development of Asteroid Taxonomic System

In 1975, Chapman, Morrison, and Zellner developed an asteroid taxonomic system based on color, albedo, and spectral shape.

1977: Discovery of 2060 Chiron

In 1977, astronomers discovered 2060 Chiron, the first small body that permanently resided further out than Jupiter.

1979: Discovery of 7968 Elst–Pizarro

In 1979, the first active asteroid, 7968 Elst–Pizarro, was initially discovered as an asteroid.

1984: Tholen Classification Proposed

In 1984, David J. Tholen proposed the Tholen classification of asteroids, based on data collected from an eight-color asteroid survey performed in the 1980s, resulting in 14 asteroid categories.

1990: Discovery of Acfer 049 Meteorite

In 1990, the Acfer 049 meteorite was discovered in Algeria.

1991: First Close-Up Photograph of 951 Gaspra

In 1991, 951 Gaspra became the first asteroid to be photographed in close-up by the Galileo probe.

1992: Discovery of 15760 Albion

In 1992, 15760 Albion was discovered, it was the first object found beyond the orbit of Neptune, excluding Pluto.

1993: Image of 243 Ida and its moon Dactyl

In 1993, the Galileo probe imaged 243 Ida and its moon Dactyl.

1994: Observation of Comet Shoemaker-Levy 9 crashing into Jupiter

In 1994, the observation of Comet Shoemaker-Levy 9 crashing into Jupiter, increased the alarm about the potential for Earth impacts.

1996: Elst and Pizarro Find Tail on Asteroid

In 1996, Eric Elst and Guido Pizarro found that 7968 Elst-Pizarro had a tail and gave it the cometary designation 133P/Elst-Pizarro.

1997: NEAR Shoemaker Photographs 253 Mathilde

In 1997, NASA's NEAR Shoemaker probe photographed asteroid 253 Mathilde.

1998: Provisional Designation of Apparition

In 1998, it was defined that when an observer finds an apparition, it gets a provisional designation, made up of the year of discovery, a letter representing the half-month of discovery, and finally a letter and a number indicating the discovery's sequential number (example: 1998 FJ74).

1999: Flyby of 9969 Braille by Deep Space 1

In 1999, the Deep Space 1 spacecraft performed a flyby of asteroid 9969 Braille.

2001: NEAR Shoemaker Lands on Eros

In 2001, the NEAR Shoemaker spacecraft successfully landed on the surface of asteroid 433 Eros, marking the first successful landing on an asteroid.

2002: Discovery of 2002 AA29

In 2002, Asteroid 2002 AA29 was discovered and found to have an unusual horseshoe orbit that is co-orbital with Earth.

2002: Provisional Designation Example

In 2002, an example provisional designation was given as 2002 AT4, which includes the year of discovery and an alphanumeric code.

2002: SMASS Classification

In 2002, the Small Main-Belt Asteroid Spectroscopic Survey resulted in a modified version of the Tholen taxonomy with 24 different types.

2002: Flyby of 5535 Annefrank by Stardust

In 2002, the Stardust spacecraft flew by asteroid 5535 Annefrank.

November 2005: Hayabusa Studies Itokawa

From September to November 2005, the Japanese Hayabusa probe studied asteroid 25143 Itokawa in detail.

2006: Main-Belt Comets Designated

In 2006, astronomers David Jewitt and Henry Hsieh originally designated active asteroids as main-belt comets (MBCs).

2006: IAU Creates Dwarf Planet Class

In 2006, the IAU created the class of dwarf planets for the largest minor planets. Ceres was placed in this category.

2006: IAU Introduces Term "Small Solar System Body"

In 2006, the International Astronomical Union (IAU) introduced the term 'small Solar System body' to broadly categorize objects in the Solar System that are neither planets, dwarf planets, nor natural satellites, including asteroids and comets.

2007: Launch of Dawn Spacecraft

In 2007, NASA launched the Dawn spacecraft, which subsequently orbited 4 Vesta for a year and observed the dwarf planet Ceres for three years.

2008: Rosetta Probe Visits Šteins and Lutetia

In 2008, the Rosetta probe briefly visited asteroids 2867 Šteins and 21 Lutetia while en route to its primary destination.

2009: Confirmation of Water Ice on 24 Themis

In 2009, the presence of water ice was confirmed on the surface of the asteroid 24 Themis using NASA's Infrared Telescope Facility. Organic compounds were also detected on the surface.

June 2010: Hayabusa Returns Samples to Earth

On June 13, 2010, the Japanese Hayabusa probe returned samples from the surface of asteroid 25143 Itokawa to Earth, marking the first asteroid sample-return mission.

August 2011: Report on DNA and RNA Components on Asteroids

In August 2011, a report based on NASA studies with meteorites found on Earth, suggested that DNA and RNA components may have been formed on asteroids and comets in outer space.

2011: Estimated Discovery Rate of Near-Earth Asteroids

As of 2011, it was estimated that 89% to 96% of near-Earth asteroids one kilometer or larger in diameter had been discovered.

2012: Chang'e 2 Flyby of Toutatis

In 2012, China's lunar orbiter Chang'e 2 flew within 3.2 km of asteroid 4179 Toutatis.

October 2013: Water Detected on Extrasolar Body

In October 2013, water was detected on an extrasolar body for the first time, specifically on an asteroid orbiting the white dwarf GD 61.

2013: Expert Testimony on Asteroid Interception Mission Preparation

According to expert testimony in the United States Congress in 2013, NASA would require at least five years of preparation before a mission to intercept an asteroid could be launched.

January 2014: Detection of Water Vapor on Ceres

On 22 January 2014, ESA scientists reported the detection of water vapor on Ceres, the largest object in the asteroid belt, using the Herschel Space Observatory.

2014: Launch of Hayabusa2

In 2014, JAXA launched the Hayabusa2 probe to asteroid 162173 Ryugu.

2016: Launch of OSIRIS-REx

In 2016, NASA launched the OSIRIS-REx mission to asteroid 101955 Bennu for sample return.

2017: Observations of Hygiea with SPHERE Imager

In 2017, observations were taken with the Very Large Telescope's SPHERE imager.

2017: Discovery of Moons around 3122 Florence

In 2017, radar imaging discovered that the asteroid 3122 Florence has two moons.

June 2018: National Near-Earth Object Preparedness Strategy Action Plan

In June 2018, the National Science and Technology Council warned that the United States is unprepared for an asteroid impact event and released the "National Near-Earth Object Preparedness Strategy Action Plan" to improve preparedness.

October 2018: LINEAR System Discoveries

As of 29 October 2018, the LINEAR system alone had discovered 147,132 asteroids, including almost 900 near-Earth asteroids larger than 1 km.

2018: Observations of Hygiea with SPHERE Imager

In 2018, observations were taken with the Very Large Telescope's SPHERE imager.

November 2019: Detection of Sugar Molecules in Meteorites

In November 2019, scientists reported detecting sugar molecules, including ribose, in meteorites, suggesting that chemical processes on asteroids can produce bio-ingredients important to life.

2019: Ultraporous Lithology Found in Acfer 049

In 2019, it was shown that the Acfer 049 meteorite has an ultraporous lithology (UPL), suggesting that UPL represents fossils of primordial ice.

2020: Hayabusa2 Returns Samples to Earth

In 2020, samples collected by Hayabusa2 from asteroid 162173 Ryugu were delivered to Earth.

2020: OSIRIS-REx Sample Collection

In 2020, the OSIRIS-REx mission studied the asteroid Bennu and collected a sample.

October 2021: Number of Near-Earth Asteroids with Moons

As of October 2021, there were 85 NEAs known to have at least one moon, including three known to have two moons.

2021: Launch of Lucy

In 2021, NASA launched Lucy, a multiple-asteroid flyby probe.

2021: Launch of NASA's Lucy Mission

In 2021, NASA launched the Lucy mission, which is tasked with studying ten different asteroids, including two from the main belt and eight Jupiter trojans.

2021: OSIRIS-REx Departs Bennu

In 2021, the OSIRIS-REx probe departed from asteroid 101955 Bennu with a sample from its surface.

April 2022: Statistics on Near-Earth Asteroids

As of April 2022, a total of 28,772 near-Earth asteroids were known; 878 have a diameter of one kilometer or larger.

September 2022: DART Impact on Dimorphos

In September 2022, the DART spacecraft deliberately crashed into Dimorphos, the minor-planet moon of the double asteroid Didymos, as part of the asteroid deflection experiment.

September 2022: Double Asteroid Redirection Test (DART) Success

In September 2022, the Double Asteroid Redirection Test spacecraft successfully altered the orbit of the non-threatening asteroid Dimorphos by crashing into it, as an experiment to meet the danger of Near-Earth asteroids.

September 2023: OSIRIS-REx Sample Delivered to Earth

In September 2023, the OSIRIS-REx mission delivered a sample from asteroid 101955 Bennu to Earth.

October 2023: Launch of Psyche

In October 2023, NASA launched the Psyche mission to study the large metallic asteroid Psyche.

October 2024: Launch of Hera

ESA launched the Hera mission in October 2024 to study the results of the DART impact on Dimorphos.

October 2024: Launch of ESA's Hera Mission

In October 2024, ESA's Hera mission was launched to study the results of the DART impact.

2024: Identification of Dark Comets

In 2024, dark comets, asteroids exhibiting non-gravitational acceleration without a coma or tail, were first identified, revealing two distinct families: the Outer Family and the Inner Family.

May 2025: Launch of Tianwen-2

CNSA's Tianwen-2 was launched in May 2025 and will explore the near-Earth asteroid 469219 Kamoʻoalewa and active asteroid 311P/PanSTARRS, collecting samples from Kamo'oalewa's regolith.

May 2025: Minor Planet Center Data Update

As of May 2025, the Minor Planet Center had data on 1,460,356 minor planets in the inner and outer Solar System, of which about 826,864 had enough information to be given numbered designations.