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Top Astronomy Stories of 2019

First images of a black hole captured by the Event Horizon Telescope

Evidence of the supermassive black hole in the center of Messier 87 and its shadow. Credit: Event Horizon Telescope Collaboration

Evidence of the supermassive black hole in the center of Messier 87 and its shadow. Credit: Event Horizon Telescope Collaboration.

In April, the Event Horizon Telescope (EHT) project announced they had taken the first-ever image of a black hole. The image, a glowing orange donut around a central black circle, showed the black hole at the center of the M87 galaxy, 55 million light-years from Earth. This black hole has a mass 6.5 billion times that of the Sun. The image opens a new window into the study of black holes.

The EHT is an international collaboration of eight radio telescopes around the world that work together to collect data. The EHT has been funded in part by the National Science Foundation. Several of GMTO’s partner institutions are involved in the EHT, including Harvard University, Smithsonian Astrophysical Observatory, the University of Arizona and the University of Chicago.

Total Solar Eclipse in Chile

The diamond ring effect. Credit: GMTO Project Manager, James Fanson.

The diamond ring effect. Credit: GMTO Project Manager, James Fanson.

On July 2, eclipse chasers from around the world gathered in Chile and Argentina to experience a total solar eclipse. Fortuitously the path of the eclipse crossed an area of Chile containing many world-class optical observatories. GMTO’s construction site was only half a kilometer from the path of totality, and we partnered with the Carnegie Institution to bring guests for a party in the desert. Many of our guests had never seen a total solar eclipse before, making the experience very special. The next total solar eclipse will take place on December 14, 2020, and will be visible in the far south of Chile. GMTO will again be taking special guests to view the eclipse.

A new measurement suggests the universe is expanding faster than we thought

The red giant stars used in the measurement of the expansion rate of the universe (circled in yellow). Credit: NASA, ESA, W. Freedman (University of Chicago), ESO, and the Digitized Sky Survey.

The red giant stars used in the measurement of the expansion rate of the universe (circled in yellow). More details here. Credit: NASA, ESA, W. Freedman (University of Chicago), ESO, and the Digitized Sky Survey.

In July, astronomers announced they had measured the expansion rate of the universe in an entirely new way, to try to resolve a discrepancy between two previous results.

The measurement was carried out using the Hubble Space Telescope by a team led by former GMTO Board Chair, and Professor of Astronomy at the University of Chicago, Prof. Wendy Freedman along with collaborators from the Carnegie Institution for Science. They measured the brightness of red giant stars in distant galaxies and compared them to the brightness of similar red giants in nearby galaxies. The difference in brightness gives an indication of distance, which can be combined with other measurements to reveal the expansion rate of the universe.

The new result sits between the previous results, leaving open the question as to whether astronomers need to revise their explanation for the birth and growth of the universe.

Interstellar visitor Comet 2I/Borisov

Comet 2l/Borisov with a background galaxy. The galaxy’s bright central core is smeared in the image because Hubble was tracking the comet. Borisov was approximately 326 million kilometers from Earth in this exposure. Credit: NASA, ESA, and D. Jewitt (UCLA)

Comet 2l/Borisov with a background galaxy. The galaxy’s bright central core is smeared in the image because Hubble was tracking the comet. Borisov was approximately 326 million kilometers from Earth in this exposure. Credit: NASA, ESA, and D. Jewitt (UCLA)

In October, the first-ever interstellar comet was spotted in our solar system. In December it made its closest approach to the Sun where the Hubble Space Telescope took its photograph. The comet was first seen by Crimean amateur astronomer Gennady Borisov in August. Images from the Hubble Space Telescope show the nucleus of the comet is just half a kilometer across, and observations from numerous telescope show that it has a very similar chemical composition to comets that originate in our solar system, providing evidence that comets also form around other stars.

Nobel Prize in Physics

Artist's impression of first exoplanet discovery 51 Pegasi b. Credit: ESO/M. Kornmesser/Nick Risinger (skysurvey.org)

Artist’s impression of first exoplanet discovery 51 Pegasi b. Credit: ESO/M. Kornmesser/Nick Risinger (skysurvey.org)

This year’s Nobel Prize in Physics was awarded to three scientists who collectively reshaped our understanding of the universe and our place within it. Half of the prize was awarded to physical cosmologist, James Peebles, for developing the theoretical framework that forms the basis of modern cosmology. The other half was awarded to Michel Mayor and Didier Queloz for the first discovery, in 1995, of a planet outside our solar system, named 51 Pegasi b. This discovery has paved the way for the more than 4,000 exoplanets discovered to date.