The universe is expanding faster than physicists would expect. To figure out what processes underlie this fast expansion rate, some researchers are first trying to rule out what processes can’t.
Telescopes at the Cerro Tololo Inter-American Observatory near La Serena, Chile.
Guillaume Doyen/CTIO/NOIRLab/NSF/AURA
Controlled experiments are impossible in astronomy, as are direct measurements of physical properties of objects outside our solar system. So how do astronomers know so much about them?
Artist concept of Gravity Probe B orbiting the Earth to measure space-time, a four-dimensional description of the universe including height, width, length, and time.
(NASA)
The gravitational field can affect space and time: the stronger gravity is, the slower time moves. This prediction of General Relativity can be used to reveal hidden forces acting on dark matter.
Astronomers can estimate ages for stars outside the Solar System, but not planets.
Corbis Historical via Getty Images
Measuring the ages of planets and stars is tricky. An observational astrophysicist describes the subtle clues that provide good estimates for how old different space objects are.
Massive flashes of energy known as ‘fast radio bursts’ have puzzled astronomers for years – and a new search for links to gravitational waves has so far found no connection.
To detect dark matter, you need to build an ultra-sensitive detector and put it somewhere ultra-quiet. For one physics collaboration, that place is almost a mile under Lead, S.D.
Bright, flickering galaxies called quasars were thought to pose a problem for our understanding of the cosmos – but new research shows Einstein was right yet again.
Black holes and other massive objects create ripples in spacetime when they merge.
Victor de Schwanburg/Science Photo Library via Getty Images
The planet Halla looks like it should have been devoured by its host star, a red giant called Baekdu – but a secret in the star’s past may hold the answer to the planet’s present.
An x-ray of the brightest ever gamma ray burst reflected off dust layers, creating extended ‘light echoes’ of the initial blast.
Nasa
One of the few examples of a fast radio burst and the slow-moving, star forming gas in its origin galaxy has been linked together – thanks to observations from a CSIRO telescope.
When two massive objects – like black holes or neutron stars – merge, they warp space and time.
Mark Garlick/Science Photo Library via Getty Images
Upgrades to the hardware and software of the advanced observatory should allow astrophysicists to detect much fainter gravitational waves than before.
New research shows that the destructive merging of a star and a planet expels huge amounts of gas, as shown in this artist’s impression.
K. Miller/R. Hurt (Caltech/IPAC)
Stars begin to expand when they run out of fuel and can become thousands of times larger, consuming any planets in the way. For the first time, astronomers have witnessed one such event.
The far side of the Moon is an attractive place to carry out astronomy.
NASA / Ernie Wright
The current race to the Moon is opening up opportunities for lunar astronomy.
SAURON: radio intensity (purple) from MeerKAT overlaid on an optical image from the Dark Energy Survey.
Michelle Lochner / The Dark Energy Survey Collaboration 2005
Beyond just looking at black holes, the next-generation Event Horizon Telescope collaboration is the first to bring together perspectives from across the sciences and humanities.