Institute of Astronomy

Astronomy News

Binary star to spill celestial secrets

5 August 2014 - 1:00am

Binary star to spill celestial secrets

Nature 512, 7512 (2014).

Author: Alexandra Witze

Close approach and violent interaction of stars in η Carinae system will provide rare insight into stellar enigma.

Rosetta:Rosetta arrives at comet 67P/C-G - follow the event live

4 August 2014 - 4:26pm
On 6 August, after a decade-long journey through space, ESA’s Rosetta will become the first spacecraft in history to rendezvous with a comet. Follow the event marking this momentous occasion at ESA's Spacecraft Operations Centre at Darmstadt, Germany.

Amazing New Photo of Rosetta Comet

2 August 2014 - 8:52pm
As the European Space Agency's Rosetta spacecraft closes to within 1000 km of Comet 67P/Churyumov-Gerasimenko, the Rosetta science team has released a new image and made the first temperature measurements of the comet's core. The temperature data show that 67P is too hot to be covered in ice and must instead have a dark, dusty crust.

Rosetta:Rosetta takes comet's temperature

1 August 2014 - 1:33pm
ESA's Rosetta spacecraft has made its first temperature measurements of its target comet, finding that it is too hot to be covered in ice and must instead have a dark, dusty crust.

Comet mission must not keep space fans in the dark

31 July 2014 - 5:57pm
The European Space Agency should change tack and not sit on pictures from a pioneering mission to a comet, says space science writer Daniel Fischer

NASA's Fermi Space Telescope Reveals New Source of Gamma Rays

31 July 2014 - 5:00pm
Observations by NASA's Fermi Gamma-ray Space Telescope of several stellar eruptions, called novae, firmly establish these relatively common outbursts almost always produce gamma rays, the most energetic form of light.

Hubble Shows Farthest Lensing Galaxy Yields Clues to Early Universe

31 July 2014 - 5:00pm
Astronomers using NASA's Hubble Space Telescope have unexpectedly discovered the most distant galaxy that acts as a cosmic magnifying glass.

Hubble Shows Farthest Lensing Galaxy Yields Clues to Early Universe

31 July 2014 - 3:00pm

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Astronomers using NASA's Hubble Space Telescope have unexpectedly discovered the most distant cosmic magnifying glass yet, produced by a monster elliptical galaxy. The galaxy, seen here as it looked 9.6 billion years ago, is so massive that its gravity bends, magnifies, and distorts light from objects behind it, a phenomenon called gravitational lensing. In the Hubble image, the galaxy is the red object in the enlarged view at left.

Rosetta:Catching up with the comet's coma

31 July 2014 - 11:13am
With the incredible images of comet 67P/Churyumov-Gerasimenko's nucleus grabbing most of the attention over the last few weeks, we shouldn't forget about the comet's coma. Of course, you can still find the most recent image of the nucleus later on in this post, but first let's talk about coma and activity.

Mystery of lemon-shaped Moon solved

30 July 2014 - 6:14pm
Tides and spin gave the Moon its strange lemon shape more than four billion years ago, research reveals.

ALMA Finds Double Star with Weird and Wild Planet-forming Discs

30 July 2014 - 6:00pm
Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have found wildly misaligned planet-forming gas discs around the two young stars in the binary system HK Tauri. These new ALMA observations provide the clearest picture ever of protoplanetary discs in a double star. The new result also helps to explain why so many exoplanets — unlike the planets in the Solar System — came to have strange, eccentric or inclined orbits. The results will appear in the journal Nature on 31 July 2014.

Leaving Earth made the moon lemon-shaped

30 July 2014 - 6:00pm
The moon has odd lemon-like bulges on each side. A new model shows they were caused by the pull of Earth's gravity when the moon was young

Pigeon paradox reveals quantum cosmic connections

30 July 2014 - 6:00pm
A thought experiment has exposed a new kind of quantum link that could connect every particle in the universe, all the time

AUDIO: Why the Moon is shaped like a lemon

30 July 2014 - 5:54pm
Professor of planetary sciences Ian Garrick-Bethell explains what gave the Moon its unusually distorted shape.

Astronomers weigh up Milky Way

30 July 2014 - 1:11am
The Milky Way is lighter than previously thought and is only about half the mass of a neighbouring galaxy, researchers conclude.

The tidal–rotational shape of the Moon and evidence for polar wander

30 July 2014 - 1:00am

The tidal–rotational shape of the Moon and evidence for polar wander

Nature 512, 7513 (2014). doi:10.1038/nature13639

Authors: Ian Garrick-Bethell, Viranga Perera, Francis Nimmo & Maria T. Zuber

The origin of the Moon’s large-scale topography is important for understanding lunar geology, lunar orbital evolution and the Moon’s orientation in the sky. Previous hypotheses for its origin have included late accretion events, large impacts, tidal effects and convection processes. However, testing these hypotheses and quantifying the Moon’s topography is complicated by the large basins that have formed since the crust crystallized. Here we estimate the large-scale lunar topography and gravity spherical harmonics outside these basins and show that the bulk of the spherical harmonic degree-2 topography is consistent with a crust-building process controlled by early tidal heating throughout the Moon. The remainder of the degree-2 topography is consistent with a frozen tidal–rotational bulge that formed later, at a semi-major axis of about 32 Earth radii. The probability of the degree-2 shape having both tidal-heating and frozen shape characteristics by chance is less than 1%. We also infer that internal density contrasts eventually reoriented the Moon’s polar axis by 36 ± 4°, to the configuration we observe today. Together, these results link the geology of the near and far sides, and resolve long-standing questions about the Moon’s large-scale shape, gravity and history of polar wander.

Misaligned protoplanetary disks in a young binary star system

30 July 2014 - 1:00am

Misaligned protoplanetary disks in a young binary star system

Nature 511, 7511 (2014). doi:10.1038/nature13521

Authors: Eric L. N. Jensen & Rachel Akeson

Many extrasolar planets follow orbits that differ from the nearly coplanar and circular orbits found in our Solar System; their orbits may be eccentric or inclined with respect to the host star’s equator, and the population of giant planets orbiting close to their host stars suggests appreciable orbital migration. There is at present no consensus on what produces such orbits. Theoretical explanations often invoke interactions with a binary companion star in an orbit that is inclined relative to the planet’s orbital plane. Such mechanisms require significant mutual inclinations between the planetary and binary star orbital planes. The protoplanetary disks in a few young binaries are misaligned, but often the measurements of these misalignments are sensitive only to a small portion of the inner disk, and the three-dimensional misalignment of the bulk of the planet-forming disk mass has hitherto not been determined. Here we report that the protoplanetary disks in the young binary system HK Tauri are misaligned by 60 to 68 degrees, such that one or both of the disks are significantly inclined to the binary orbital plane. Our results demonstrate that the necessary conditions exist for misalignment-driven mechanisms to modify planetary orbits, and that these conditions are present at the time of planet formation, apparently because of the binary formation process.

‘Go’ for science

29 July 2014 - 2:42pm

Following the extensive in-orbit commissioning review and after encountering the unexpected challenges highlighted previously on the blog, Gaia is now ready to begin its science mission.

Read the announcement published today on the ESA Portal: Gaia: 'Go' for science

And for a full quantitative analysis of Gaia’s expected science performance based on the results of commissioning, see: Commissioning review: Gaia ready to start routine operations

Gaia:Gaia: 'Go' for science

29 July 2014 - 1:58pm
Following extensive in-orbit commissioning and several unexpected challenges, ESA's billion-star surveyor, Gaia, is now ready to begin its science mission.

Perseid Meteors vs. the Supermoon

28 July 2014 - 11:54pm
Which is brighter--a flurry of Perseid fireballs or a supermoon? Sky watchers will find out this August when the biggest and brightest full Moon of 2014 arrives just in time for the peak of the annual Perseid meteor shower.