Institute of Astronomy

Astronomy News

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.

Mars Rover Sets Off-World Driving Record

28 July 2014 - 9:30pm
NASA's Opportunity Mars rover, which landed on the Red Planet in 2004, now holds the off-Earth roving distance record after accruing 25 miles (40 kilometers) of driving, and is not far from completing the first extraterrestrial marathon. The previous record was held by the Soviet Union's Lunokhod 2 rover.

Venus Express:Venus Express: up above the clouds so high

28 July 2014 - 5:50pm
ESA's Venus Express spacecraft has climbed to a new orbit following its daring aerobraking experiment, and will now resume observations of this fascinating planet for at least a few more months.

NASA’s Long-Lived Mars Opportunity Rover Sets Off-World Driving Record

28 July 2014 - 5:00pm
NASA's Opportunity Mars rover, which landed on the Red Planet in 2004, now holds the off-Earth roving distance record after accruing 25 miles (40 kilometers) of driving. The previous record was held by the Soviet Union's Lunokhod 2 rover.

Cassini Spacecraft Reveals 101 Geysers and more on Icy Saturn Moon

28 July 2014 - 5:00pm
Scientists using mission data from NASA’s Cassini spacecraft have identified 101 distinct geysers erupting on Saturn’s icy moon Enceladus. Their analysis suggests it is possible for liquid water to reach from the moon’s underground sea all the way to its surface.

101 Geysers on Icy Saturn Moon

28 July 2014 - 1:07am
Scientists using mission data from NASA’s Cassini spacecraft have identified 101 distinct geysers erupting on Saturn’s icy moon Enceladus. Their analysis suggests it is possible for liquid water to reach from the moon’s underground sea all the way to its surface.

The origin of the local 1/4-keV X-ray flux in both charge exchange and a hot bubble

27 July 2014 - 1:00am

The origin of the local 1/4-keV X-ray flux in both charge exchange and a hot bubble

Nature 512, 7513 (2014). doi:10.1038/nature13525

Authors: M. Galeazzi, M. Chiao, M. R. Collier, T. Cravens, D. Koutroumpa, K. D. Kuntz, R. Lallement, S. T. Lepri, D. McCammon, K. Morgan, F. S. Porter, I. P. Robertson, S. L. Snowden, N. E. Thomas, Y. Uprety, E. Ursino & B. M. Walsh

The solar neighbourhood is the closest and most easily studied sample of the Galactic interstellar medium, an understanding of which is essential for models of star formation and galaxy evolution. Observations of an unexpectedly intense diffuse flux of easily absorbed 1/4-kiloelectronvolt X-rays, coupled with the discovery that interstellar space within about a hundred parsecs of the Sun is almost completely devoid of cool absorbing gas, led to a picture of a ‘local cavity’ filled with X-ray-emitting hot gas, dubbed the local hot bubble. This model was recently challenged by suggestions that the emission could instead be readily produced within the Solar System by heavy solar-wind ions exchanging electrons with neutral H and He in interplanetary space, potentially removing the major piece of evidence for the local existence of million-degree gas within the Galactic disk. Here we report observations showing that the total solar-wind charge-exchange contribution is approximately 40 per cent of the 1/4-keV flux in the Galactic plane. The fact that the measured flux is not dominated by charge exchange supports the notion of a million-degree hot bubble extending about a hundred parsecs from the Sun.