Category Astronomy/Space

This is an artist impression of the triple star system PSR J0337+1715, which is located about 4,200 light-years from Earth. This system provides a natural laboratory to test fundamental theories of gravity. Credit: NRAO/AUI/NSF; S. Dagnello

Einstein’s understanding of gravity, as outlined in his general theory of relativity, predicts that all objects fall at the same rate, regardless of their mass or composition. This theory has passed test after test here on Earth, but does it still hold true for some of the most massive and dense objects in the known universe, an aspect of nature known as the Strong Equivalence Principle? An international team of astronomers has given this lingering question its most stringent test ever...

An impression of the encounter between the Milky Way galaxy and the smaller Sausage galaxy about 8 billion to 10 billion years ago. The record of this ancient encounter is still preserved in the velocities and chemistry of the stars.
Credit: V. Belokurov (Cambridge, UK); Based on image by ESO/Juan Carlos Muñoz

An international team has discovered an ancient and dramatic head-on collision between the Milky Way and a smaller object, dubbed the “Sausage” galaxy. The cosmic crash was a defining event in the early history of the Milky Way and reshaped the structure of our galaxy, fashioning both its inner bulge and its outer halo, the astronomers report in a series of new papers.

The astronomers propose that around 8 billion to 10 billion years ago, an unknown dwarf galaxy smashed into our own ...

The collision with Uranus of a massive object twice the size of Earth that caused the planet’s unusual spin, from a high-resolution simulation using over ten million particles, coloured by their internal energy.
Credit: Jacob Kegerreis/Durham University

Uranus was hit by a massive object roughly twice the size of Earth that caused the planet to tilt and could explain its freezing temperatures, according to new research. Astronomers at Durham University, UK, led an international team of experts to investigate how Uranus came to be tilted on its side and what consequences a giant impact would have had on the planet’s evolution.

The team ran the first high-resolution computer simulations of different massive collisions with the ice giant to try to work out how the planet evolved...

View of comet 67P taken by Rosetta.
Credit: European Space Agency

Scientists have found that molecular oxygen around comet 67P is not produced on its surface, as some suggested, but may be from its body. The European Space Agency’s Rosetta spacecraft escorted comet 67P/Churyumov-Gerasimenko on its journey round the sun from August 2014 – September 2016, dropping a probe and eventually crashing onto its surface.

When the comet is close enough to the sun the ice on its surface ‘sublimes’ – transforms from solid to gas – forming a gas atmosphere called a coma. Analysis of the coma by instruments on Rosetta revealed that it contained not only water, CO and CO2, as anticipated, but also molecular oxygen.

Molecular oxygen is O2, and on Earth it is essential for life, where it is produced by photo...