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Shrinking Mercury is tectonically active

28 September 2016 Astronomy Now

Images from NASA’s MESSENGER spacecraft reveal previously undetected cliff-like landforms on Mercury that scientists believe must be geologically young, which means that the innermost planet is still contracting and that Earth is not the only tectonically active planet in our solar system, as previously thought.

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Chandra X-ray Observatory finds evidence for violent stellar merger

16 July 2016 Astronomy Now

Gamma-ray bursts, or GRBs, are some of the most violent and energetic events in the universe. Although these events are the most luminous explosions astronomers can observe, a new study using NASA’s Chandra X-ray Observatory, NASA’s Swift satellite and other Earth-based telescopes suggests that scientists may be missing a majority of these powerful cosmic detonations.

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Behind the scenes of protostellar disc formation

11 July 2016 Astronomy Now

For a long time the formation of protostellar discs — a prerequisite to the formation of planetary systems — has defied theoretical astrophysicists. Now, researchers have made a breakthrough in our understanding of how protoplanetary discs form, demonstrating that chemistry and microphysics are crucial to the fundamental processes underlying star and planet formation.

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The curious case of Earth’s leaking atmosphere

8 July 2016 Astronomy Now

Overall, about 1 kg of material is escaping our atmosphere every second. Every day, around 90 tonnes of material escapes from our planet’s upper atmosphere and streams out into space. Although missions such as ESA’s Cluster fleet have long been investigating this leakage, there are still many open questions. How and why is Earth losing its atmosphere?

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The spider in the loop

23 June 2016 Astronomy Now

This multicoloured swirl of yellow and blue shows a prominent ring of gas near the North Celestial Pole. The pole appears to be fixed in place, while the rest of the night sky slowly circles around it because of Earth’s rotation. This image comes courtesy of ESA’s Planck satellite, which spent years mapping the entire sky in exquisite detail between 2009 and 2013.

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Sun’s adolescent storms may have been key to life on Earth

24 May 2016 Astronomy Now

Some 4 billion years ago, the Sun shone with only about three-quarters the brightness we see today, but its surface roiled with giant eruptions spewing enormous amounts of radiation into space. These powerful solar explosions may have provided the crucial energy needed to create greenhouse gas in Earth’s atmosphere, warming the planet and incubating life.

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‘Starspot’ images of nearby star give insights into early Sun

4 May 2016 Astronomy Now

Astronomers have used interferometry to create a time-lapse of the nearby star zeta Andromedae over one of its 18-day rotations that show starspots — sunspots outside our solar system. The pattern of spots on the star is very different from their typical arrangement on our Sun, challenging current theories of how stars’ magnetic fields influence their evolution.

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Moon thought to play major role in maintaining Earth’s magnetic field

1 April 2016 Astronomy Now

The Earth’s magnetic field is produced by the geodynamo, the rapid motion of huge quantities of liquid iron alloy in the Earth’s outer core. A team of French researchers suggests that elastic deformation of our planet’s mantle due to tidal effects caused by the Moon — overlooked until now — transfers energy to the Earth’s outer core, keeping the geodynamo active.

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Understanding the magnetic Sun

30 January 2016 Astronomy Now

The Sun’s magnetic field is responsible for everything from the solar explosions that cause space weather on Earth — such as aurorae — to the interplanetary magnetic field and radiation through which our spacecraft journeying around the solar system must travel. But even now, scientists are not sure exactly where in the Sun the magnetic field is created.