Answer to Question #110863 in English for Felicia Ngubandze

Question

Discuss the important discoveries in astronomy by different people in the last 100 years.

Answer 1

1923

Edwin Hubble discovers a Cepheid variable star in the "Andromeda Nebula" and proves that Andromeda and other nebulas are galaxies far beyond our own. By 1925, he produces a classification system for galaxies.

1925

Cecilia Payne-Gaposchkin discovers that hydrogen is the most abundant element in the Sun's atmosphere, and accordingly, the most abundant element in the universe by relating the spectral classes of stars to their actual temperatures and by applying the ionization theory developed by Indian physicist Meghnad Saha. This opens the path for the study of stellar atmospheres and chemical abundances, contributing to understand the chemical evolution of the universe.

1926

Robert Goddard launches the first rocket powered by liquid fuel. He also demonstrates that a rocket can work in a vacuum. His later rockets break the sound barrier for the first time.

1929

Edwin Hubble discovered that the universe is expanding and that the farther away a galaxy is, the faster it is moving away from us. Two years later, Georges Lemaître suggests that the expansion can be traced to an initial "Big Bang".

1930

By applying new ideas from subatomic physics, Subrahmanyan Chandrasekhar predicts that the atoms in a white dwarf star of more than 1.44 solar masses will disintegrate, causing the star to collapse violently. In 1933, Walter Baade and Fritz Zwicky describe the neutron star that results from this collapse, causing a supernova explosion.

Clyde Tombaugh discovers the dwarf planet Pluto at the Lowell Observatory in Flagstaff, Arizona. The object is so faint and moving so slowly that he has to compare photos taken several nights apart.

1932

Karl Jansky detects the first radio waves coming from space. In 1942, radio waves from the Sun are detected. Seven years later radio astronomers identify the first distant source - the Crab Nebula, and the galaxies Centaurus A and M87.

1938

German physicist Hans Bethe explains how stars generate energy. He outlines a series of nuclear fusion reactions that turn hydrogen into helium and release enormous amounts of energy in a star's core. These reactions use the star's hydrogen very slowly, allowing it to burn for billions of years.

1944

A team of German scientists led by Wernher von Braun develops the V-2, the first rocket-powered ballistic missile. Scientists and engineers from Braun's team were captured at the end of World War II and drafted into the American and Russian rocket programs.

1948

The largest telescope in the world, with a 5.08m (200 in) mirror, is completed at Palomar Mountain in California. At the time, the telescope pushes single-mirror telescope technology to its limits - large mirrors tend to bend under their own weight.

1957

Russia launches the first artificial satellite, Sputnik 1, into orbit, beginning the space age. The US launches its first satellite, Explorer 1, four months later.

1958

July 29 marks the beginning of the NASA (National Aeronautics and Space Administration), agency newly created by the United States to catch up with Soviet space technologies. It absorbs all research centers and staffs of the NACA (National Advisory Committee for Aeronautics), an organization founded in 1915.

1959

Russia and the US both launch probes to the Moon, but NASA's Pioneer probes all failed. The Russian Luna program was more successful. Luna 2 crash-lands on the Moon's surface in September, and Luna 3 returns the first pictures of the Moon's farside in October.

1960

Cornell University astronomer Frank Drake performed the first modern SETI experiment, named "Project Ozma", after the Queen of Oz in L. Frank Baum's fantasy books.

1961

Russia takes the lead in the space race as Yuri Gagarin becomes the first person to orbit Earth in April. NASA astronaut Alan Shepard becomes the first American in space a month later, but does not go into orbit, although he is the first person to land with himself still inside his spacecraft thus technically achieving the first complete human spaceflight by FAI definitions. John Glenn achieves orbit in early 1962.

1962

Mariner 2 becomes the first probe to reach another planet, flying past Venus in December. NASA follows this with the successful Mariner 4 mission to Mars in 1965, both the US and Russia send many more probes to planets through the rest of the 1960s and 1970s.

1963

Dutch-American astronomer Maarten Schmidt measures the spectra of quasars, the mysterious star-like radio sources discovered in 1960. He establishes that quasars are active galaxies, and among the most distant objects in the universe.

1965

Arno Penzias and Robert Wilson announce the discovery of a weak radio signal coming from all parts of the sky. Scientists figure out that this must be emitted by an object at a temperature of -270 °C. Soon it is recognized as the remnant of the very hot radiation from the Big Bang that created the universe 13 billion years ago, see Cosmic microwave background. This radio signal is emitted by the electron in hydrogen flipping from pointing up or down and is approximated to happen once in a million years for every particle. Hydrogen is present in interstellar space gas throughout the entire universe and most dense in nebulae which is where the signals originate. Even though the electron of hydrogen only flips once every million years the mere quantity of hydrogen in space gas makes the presence of these radio waves prominent.

1966

Russian Luna 9 probe makes the first successful soft landing on the Moon in January, while the US lands the far more complex Surveyor missions, which follows up to NASA's Ranger series of crash-landers, scout sites for possible manned landings.

1967

Jocelyn Bell Burnell and Antony Hewish detected the first pulsar, an object emitting regular pulses of radio waves. Pulsars are eventually recognized as rapidly spinning neutron stars with intense magnetic fields - the remains of a supernova explosion.

1968

NASA's Apollo 8 mission becomes the first human spaceflight mission to enter the gravitational influence of another celestial body and to orbit it.

1969

The US wins the race for the Moon as Neil Armstrong and Buzz Aldrin step onto the lunar surface on July 20. Apollo 11 is followed by five further landing missions, three carrying a sophisticated Lunar Roving Vehicle.

1970

The Uhuru satellite, designed to map the sky at X-ray wavelengths, is launched by NASA. The existence of X-rays from the Sun and a few other stars has already been found using rocket-launched experiments, but Uhuru charts more than 300 X-ray sources, including several possible black holes.

1971

Russia launches its first space station Salyut 1 into orbit. It is followed by a series of stations, culminating with Mir in 1986. A permanent platform in orbit allows cosmonauts to carry out serious research and to set a series of new duration records for spaceflight.

1972

Charles Thomas Bolton was the first astronomer to present irrefutable evidence of the existence of a black hole.

1975

The Russian probe Venera 9 lands on the surface of Venus and sends back the first picture of its surface. The first probe to land on another planet, Venera 7 in 1970, had no camera. Both break down within an hour in the hostile atmosphere.

1976

NASA's Viking 1 and Viking 2 space probes arrive at Mars. Each Viking mission consists of an orbiter, which photographs the planet from above, and a lander, which touches down on the surface, analyzes the rocks, and searches unsuccessfully for life.

1977

On August 20 the Voyager 2 space probe launched by NASA to study the Jovian system, Saturnian system, Uranian system, Neptunian system, the Kuiper belt, the heliosphere and the interstellar space.

On September 5 The Voyager 1 space probe launched by NASA to study the Jovian system, Saturnian system and the interstellar medium.

1981

Space Shuttle Columbia, the first of NASA's reusable Space Shuttles, makes its maiden flight, ten years in development, the Shuttle will make space travel routine and eventually open the path for a new International Space Station.

1983

The first infrared astronomy satellite, IRAS, is launched. It must be cooled to extremely low temperatures with liquid helium, and it operates for only 300 days before the supply of helium is exhausted. During this time it completes an infrared survey of 98% of the sky.

1986

NASA's spaceflight program comes to a halt when Space Shuttle Challenger explodes shortly after launch. A thorough inquiry and modifications to the rest of the fleet kept the shuttles on the ground for nearly three years.

The returning Halley's Comet is met by a fleet of five probes from Russia, Japan, and Europe. The most ambitious is the European Space Agency's Giotta spacecraft, which flies through the comet's coma and photographs the nucleus.

1990

The Magellan probe, launched by NASA, arrives at Venus and spends three years mapping the planet with radar. Magellan is the first in a new wave of probes that include Galileo, which arrives at Jupiter in 1995, and Cassini which arrives at Saturn in 2004.

The Hubble Space Telescope, the first large optical telescope in orbit, is launched using the Space Shuttle, but astronomers soon discovered that it is crippled by a problem with its mirror. A complex repair mission in 1993 allows the telescope to start producing spectacular images of distant stars, nebulae, and galaxies.

1992

The Cosmic Background Explorer satellite produces a detailed map of the background radiation remaining from the Big Bang. The map shows "ripples", caused by slight variations in the density of the early universe – the seeds of galaxies and galaxy clusters.

The 10-meter Keck telescope on Mauna Kea, Hawaii, is completed. The first revolutionary new wave of telescopes, the Keck's main mirror is made of 36 six-sided segments, with computers to control their alignment. New optical telescopes also make use of interferometry – improving resolution by combining images from separate telescopes.

1995

The first exoplanet, 51 Pegasi b, is discovered by Michel Mayor and Didier Queloz.

1998

Construction work on a huge new space station named ISS has begun. A joint venture between many countries, including former space rivals Russia and the US.

2005

Mike Brown and his team discovered Eris a large body in the outer Solar System which was temporarily named as (2003) UB313. Initially, it appeared larger than Pluto and was called the tenth planet.

2006

International Astronomical Union (IAU) adopted a new definition of planet. A new distinct class of objects called dwarf planets was also decided. Pluto was redefined as a dwarf planet along with Ceres and Eris, formerly known as (2003) UB313. Eris was named after the IAU General Assembly in 2006.

2008

2008 TC3 becomes the first Earth-impacting meteoroid spotted and tracked prior to impact.

2012

(May 2) First visual proof of existence of black holes is published. Suvi Gezari's team in Johns Hopkins University, using the Hawaiian telescope Pan-STARRS 1, record images of a supermassive black hole 2.7 million light-years away that is swallowing a red giant.

2013

In October 2013, the first extrasolar asteroid is detected around white dwarf star GD 61. It is also the first detected extrasolar body which contains water in liquid or solid form

2015

On July 14, with the successful encounter of Pluto by NASA's New Horizons spacecraft, the United States became the first nation to explore all of the nine major planets recognized in 1981. Later on September 14, LIGO was the first to directly detect gravitational waves.

2016

Exoplanet Proxima Centauri b is discovered around Proxima Centauri by the European Southern Observatory, making it the closest known exoplanet to the Solar System as of 2016.

2017

In August 2017, a neutron star collision that occurred in the galaxy NGC 4993 produced the gravitational wave signal GW170817, which was observed by the LIGO/Virgo collaboration. After 1.7 seconds, it was observed as the gamma-ray burst GRB 170817A by the Fermi Gamma-ray Space Telescope and INTEGRAL, and its optical counterpart SSS17a was detected 11 hours later at the Las Campanas Observatory. Further optical observations e.g. by the Hubble Space Telescope and the Dark Energy Camera, ultraviolet observations by the Swift Gamma-Ray Burst Mission, X-ray observations by the Chandra X-ray Observatory and radio observations by the Karl G. Jansky Very Large Array complemented the detection. This was the first instance of a gravitational wave event that was observed to have a simultaneous electromagnetic signal, thereby marking a significant breakthrough for multi-messenger astronomy. Non-observation of neutrinos is attributed to the jets being strongly off-axis.

2019

China's Chang'e 4 became the first spacecraft to perform a soft landing on the lunar far side.

In April 2019, the Event Horizon Telescope Collaboration obtained the first image of a black hole which was at the center of galaxy M87, providing more evidence for the existence of supermassive black holes in accordance with general relativity.

India launched its second lunar probe called Chandrayaan 2 with an orbiter that was successful and a lander called Vikram along with a rover called Pragyan which failed just 2.1 km above the lunar south pole.

2020

NASA proposes to launch Mars 2020 to Mars with a Mars rover which was named Perseverance by a seventh grader Alexander Mather in a naming contest.