Institute of Astronomy

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Philae's sensors show comet 67P has almost no magnetic field

Astronomy News - 15 April 2015 - 9:37am
Comet 67P/Churyumov–Gerasimenko surprisingly has a negligible magnetic field, which has implications for how planets formed

Comet lander tells magnetic story

Astronomy News - 15 April 2015 - 9:25am

The comet being trailed through space by Europe's Rosetta probe has no magnetic field of its own - an important observation in the understanding of how the icy dirt-ball formed billions of years ago.

Coloured Pluto comes into view

Astronomy News - 15 April 2015 - 9:25am

The New Horizons probe, which is bearing down on Pluto, has captured its first colour image of the distant dwarf planet.

Dark matter becomes less 'ghostly'

Astronomy News - 15 April 2015 - 9:24am

Scientists have uncovered a vital new insight into the nature of dark matter.

Solar Orbiter launch moved to 2018

Astronomy News - 14 April 2015 - 9:46am

The launch of Solar Orbiter, an ESA mission to explore the Sun in unprecedented detail, is now planned to take place in October 2018. The launch was previously targeted for July 2017.

Final chance to present a talk or poster at the 2015 National Astronomy Meeting!...

Astronomy News - 14 April 2015 - 9:46am
Final chance to present a talk or poster at the 2015 National Astronomy Meeting!

The extended abstract deadline is tomorrow, Tues 14 April

National Astronomy Meeting 2015
National Astronomy Meeting 2015

Two mysterious bright spots on dwarf planet Ceres are not alike

Astronomy News - 14 April 2015 - 9:45am
The bright spots on the dwarf planet Ceres continue to baffle scientists as infrared images reveal they have different thermal properties

Dwarf Ceres captured in colour

Astronomy News - 14 April 2015 - 9:16am

The US space agency's Dawn mission to Ceres has released its first colour map of the dwarf planet.

Evidence of liquid water on Mars

Astronomy News - 14 April 2015 - 9:16am

Nasa's Curiosity rover has found that water can exist as a liquid near the Martian surface.

Dark matter map yields first results

Astronomy News - 14 April 2015 - 9:05am

A huge effort to make a map of dark matter, the invisible stuff holding galaxies in place across the cosmos, releases its first batch of results.

Native Hawaiians halt construction of giant telescope

Astronomy News - 13 April 2015 - 8:51am

The Thirty Meter Telescope being built atop Mauna Kea flouts environmental rules and desecrates sacred ground, say native Hawaiian activists

Looking into the voids could help explain dark energy

Astronomy News - 13 April 2015 - 8:51am

The influence of dark energy on big empty patches in space could aid us in understanding the expansion of the universe – and predicting its ultimate fate

Heart of the black auroras revealed by Cluster

Astronomy News - 10 April 2015 - 9:37am

Most people have heard of auroras - more commonly known as the Northern and Southern Lights - but, except on rare occasions, such as the recent widespread apparition on 17 March, they are not usually visible outside the polar regions. Less familiar are phenomena known as black auroras, dark patches which often subdivide the glowing curtains of red and green light.

Our Sun Came Late to the Milky Way's Star-Birth Party

Astronomy News - 10 April 2015 - 9:36am

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Our Sun missed the stellar "baby boom" that erupted in our young Milky Way galaxy 10 billion years ago. During that time the Milky Way was churning out stars 30 times faster than it does today. Our galaxy was ablaze with a firestorm of star birth as its rich reservoir of hydrogen gas compressed under gravity, creating myriad stars. But our Sun was not one of them. It was a late "boomer," arising 5 billion years later, when star birth had plunged to a trickle.

Citizen Scientists Discover Yellow "Space Balls"

Astronomy News - 10 April 2015 - 9:35am
Citizen scientists scanning images from a NASA observatory have found "yellow balls" in space that may hold important clues to the mysteries of starbirth.

Complex Organic Molecules Discovered in Infant Star System

Astronomy News - 9 April 2015 - 9:42am
For the first time, astronomers have detected the presence of complex organic molecules, the building blocks of life, in a protoplanetary disc surrounding a young star. The discovery, made with the Atacama Large Millimeter/submillimeter Array (ALMA), reaffirms that the conditions that spawned the Earth and Sun are not unique in the Universe. The results are published in the 9 April 2015 issue of the journal Nature.

A primordial origin for the compositional similarity between the Earth and the Moon

Astronomy News - 9 April 2015 - 9:40am

A primordial origin for the compositional similarity between the Earth and the Moon

Nature 520, 7546 (2015). doi:10.1038/nature14333

Authors: Alessandra Mastrobuono-Battisti, Hagai B. Perets & Sean N. Raymond

Most of the properties of the Earth–Moon system can be explained by a collision between a planetary embryo (giant impactor) and the growing Earth late in the accretion process. Simulations show that most of the material that eventually aggregates to form the Moon originates from the impactor. However, analysis of the terrestrial and lunar isotopic compositions show them to be highly similar. In contrast, the compositions of other Solar System bodies are significantly different from those of the Earth and Moon, suggesting that different Solar System bodies have distinct compositions. This challenges the giant impact scenario, because the Moon-forming impactor must then also be thought to have a composition different from that of the proto-Earth. Here we track the feeding zones of growing planets in a suite of simulations of planetary accretion, to measure the composition of Moon-forming impactors. We find that different planets formed in the same simulation have distinct compositions, but the compositions of giant impactors are statistically more similar to the planets they impact. A large fraction of planet–impactor pairs have almost identical compositions. Thus, the similarity in composition between the Earth and Moon could be a natural consequence of a late giant impact.

Saturn’s fast spin determined from its gravitational field and oblateness

Astronomy News - 9 April 2015 - 9:39am

Saturn’s fast spin determined from its gravitational field and oblateness

Nature 520, 7546 (2015). doi:10.1038/nature14278

Authors: Ravit Helled, Eli Galanti & Yohai Kaspi

The alignment of Saturn’s magnetic pole with its rotation axis precludes the use of magnetic field measurements to determine its rotation period. The period was previously determined from radio measurements by the Voyager spacecraft to be 10 h 39 min 22.4 s (ref. 2). When the Cassini spacecraft measured a period of 10 h 47 min 6 s, which was additionally found to change between sequential measurements, it became clear that the radio period could not be used to determine the bulk planetary rotation period. Estimates based upon Saturn’s measured wind fields have increased the uncertainty even more, giving numbers smaller than the Voyager rotation period, and at present Saturn’s rotation period is thought to be between 10 h 32 min and 10 h 47 min, which is unsatisfactory for such a fundamental property. Here we report a period of 10 h 32 min 45 s ± 46 s, based upon an optimization approach using Saturn’s measured gravitational field and limits on the observed shape and possible internal density profiles. Moreover, even when solely using the constraints from its gravitational field, the rotation period can be inferred with a precision of several minutes. To validate our method, we applied the same procedure to Jupiter and correctly recovered its well-known rotation period.

The comet-like composition of a protoplanetary disk as revealed by complex cyanides

Astronomy News - 9 April 2015 - 9:39am

The comet-like composition of a protoplanetary disk as revealed by complex cyanides

Nature 520, 7546 (2015). doi:10.1038/nature14276

Authors: Karin I. Öberg, Viviana V. Guzmán, Kenji Furuya, Chunhua Qi, Yuri Aikawa, Sean M. Andrews, Ryan Loomis & David J. Wilner

Observations of comets and asteroids show that the solar nebula that spawned our planetary system was rich in water and organic molecules. Bombardment brought these organics to the young Earth’s surface. Unlike asteroids, comets preserve a nearly pristine record of the solar nebula composition. The presence of cyanides in comets, including 0.01 per cent of methyl cyanide (CH3CN) with respect to water, is of special interest because of the importance of C–N bonds for abiotic amino acid synthesis. Comet-like compositions of simple and complex volatiles are found in protostars, and can readily be explained by a combination of gas-phase chemistry (to form, for example, HCN) and an active ice-phase chemistry on grain surfaces that advances complexity. Simple volatiles, including water and HCN, have been detected previously in solar nebula analogues, indicating that they survive disk formation or are re-formed in situ. It has hitherto been unclear whether the same holds for more complex organic molecules outside the solar nebula, given that recent observations show a marked change in the chemistry at the boundary between nascent envelopes and young disks due to accretion shocks. Here we report the detection of the complex cyanides CH3CN and HC3N (and HCN) in the protoplanetary disk around the young star MWC 480. We find that the abundance ratios of these nitrogen-bearing organics in the gas phase are similar to those in comets, which suggests an even higher relative abundance of complex cyanides in the disk ice. This implies that complex organics accompany simpler volatiles in protoplanetary disks, and that the rich organic chemistry of our solar nebula was not unique.

Solar System: An incredible likeness of being

Astronomy News - 9 April 2015 - 9:39am

Solar System: An incredible likeness of being

Nature 520, 7546 (2015). doi:10.1038/520169a

Authors: Robin M. Canup

Earth and the Moon share many puzzling chemical similarities. New analyses show that the last planet-sized body to hit Earth could have been similar enough to Earth to yield a Moon with an Earth-like composition. See Letter p.212