28
Jan 15

Cometary globule CG4 aka the Mouth of the Beast

Source: Photo Release eso1503

VLT image of the cometary globule CG4VLT image of the cometary globule CG4.
Image credits:ESO

Like the gaping mouth of a gigantic celestial creature, the cometary globule CG4 glows menacingly in this new image from ESO’s Very Large Telescope. Although it appears to be big and bright in this picture, this is actually a faint nebula, which makes it very hard for amateur astronomers to spot. The exact nature of CG4 remains a mystery.(read more)

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27
Jan 15

The Rolling Hills of Mercury

Friday_January_23
This incredible image attests to how the MESSENGER spacecraft is now able to resolve Mercury's surface: with a resolution of a little more than five meters (seventeen feet) per pixel, a person of average walking pace could cross this scene in about an hour. The image shows the fine texture on the inner wall of an unnamed impact basin 100 km (62 mi.) in diameter, situated immediately west of the larger Dali basin. Both this basin and its larger neighbor are filled with smooth plains and deformed by lobate scarps and wrinkle ridges.
This image was acquired as a high-resolution targeted observation. Targeted observations are images of a small area on Mercury's surface at resolutions much higher than the 200-meter/pixel morphology base map. It is not possible to cover all of Mercury's surface at this high resolution, but typically several areas of high scientific interest are imaged in this mode each week.
The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft's seven scientific instruments and radio science investigation are unraveling the history and evolution of the Solar System's innermost planet. In the mission's more than three years of orbital operations, MESSENGER has acquired over 250,000 images and extensive other data sets. MESSENGER is capable of continuing orbital operations until early 2015.
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26
Jan 15

Science reveals Rosetta's research on comet 67P/Churyumov-Gerasimenko (67P)

Source: Science

Comet-67P-grand-viewLandscape on the smaller of the two lobes of Comet 67P/Churyumov-Gerasimenko
taken from a distance of  just 5 miles (8 km).
Image credit: ESA/Rosetta/MPS for OSIRIS Team
MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

A series of scientific papers in journal Science published on January 23rd offers a complete, if preliminary, look at Rosetta’s comet. And what a wonderful and complex world it is.

Taylor & al. made an abstract of the articles that states that the surface of the comet shows evidence of many active processes and is highly complex. The solid nucleus is an object for which neither horizontal nor vertical variations are modest. He also says that the current comet shape model suggests that the mass is 1013 kg (about 100 million times the mass of the international space station), with a bulk density of ~470 kg/m3 (similar to cork, wood, or aerogel). The low mass and density values strongly constrain the composition and internal structure of the nucleus, implying a relatively fluffy nature, with a porosity of 70 to 80%". There is also some ideas about nucleus surface that appears rich in organic materials, with little sign of water ice.

It seems also that the coma produced by ices sublimating from the nucleus is highly variable, displaying large diurnal and possibly seasonal changes. (learn more)

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11
Jan 15

Mercury and Venus in Conjunction in January

Source: Astronomy Magazine

150106-004-Venus-MercuryVenus & Mercury at dusk on the 6th of January.
Image credits: Derek Rowley.

Mercury reaches greatest elongation on 14th of January, when it lies 19° east of the Sun and hangs 10° above the southwestern horizon a half-hour after sunset. Although the innermost planet glows brightly, at magnitude –0.7, the easiest way to find it is to look 1.3° to the right of brilliant Venus. Binoculars will show you the pair best. When viewed through a telescope, Mercury appears 7" across and slightly more than half-lit.

MercuryandVenusUse brilliant Venus as a guide to its fainter companion Mercury on the 14th of January.
Image credits: Astronomy/Roen Kelly.

 

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11
Jan 15

Don't miss comet Lovejoy

Source: Universe Today

Lovejoy-photo-chart-Orion_V4Comet Lovejoy’s nightly position among the winter stars through January 19.
Image credit: Bob King.

Beautiful New Year’s comet – Comet C/2014 Q2 Lovejoy – passed closest to Earth on January 7, 2015 and therefore (probably) now appears at its brightest in our sky. On January 7, it was 70.2 million km away and shining at an apparent magnitude of +4. Many across the globe have already seen this comet as it has brightened in recent weeks. Plus, the moon is no longer a hindrance. More good news. The comet has been moving northward on the sky’s dome. On January 9, it crossed over into the easy-to-find constellation Taurus (the Bull). Look to the photo above to try to spot it in the night sky. (learn more)

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10
Jan 15

Never before seen new impact crater on Mars

Source: Universe Today

ESP_039148_1980-580x374Before and after.
Image credit: NASA/JPL/UA

The surface of Mars is a well worn place in the Solar System, heavily pounded by countless meteor impacts. And some of these craters are hundreds of millions of years old. So it’s unusual for there to be a completely fresh impact on the surface of Mars: but that’s just what NASA scientists discovered looking through a recent batch of images returned from NASA’s Mars Reconnaissance Orbiter.

You’re looking at a composite of two images taken by the Mars Context Camera, an instrument on board the Mars Reconnaissance Orbiter the most recnt one on the right and an older photograph taken of the same region in February 2012 on the left. On the older one there was just a bunch of old craters. And then, in the newer image, taken June 2014, this fresh scar on the surface of Mars is clearly visible. (learn more)

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8
Jan 15

Hubble captures the sharpest ever view of neighbouring spiral Galaxy

Source: ESA/Hubble Photo Release heic1502

Sharpest ever view of the Andromeda GalaxyAndromeda Galaxy.
Image credits: NASAESA, J. Dalcanton (University of Washington, USA),
B. F. Williams (University of Washington, USA), L. C. Johnson
(University of Washington, USA), the PHAT team, and R. Gendler.

The NASA/ESA Hubble Space Telescope has captured the sharpest and biggest image ever taken of the Andromeda galaxy — otherwise known as Messier 31. The enormous image is the biggest Hubble image ever released and shows over 100 million stars and thousands of star clusters embedded in a section of the galaxy’s pancake-shaped disc stretching across over 40 000 light-years.(learn more)

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8
Jan 15

Hubble captures the Pillars of Creation twenty years on

Source: ESA/Hubble Photo Release heic1501

heic1501aThe Pillars of Creation.
Image credit: NASAESA/Hubble and the Hubble Heritage Team

The NASA/ESA Hubble Space Telescope has captured many breathtaking images of the Universe, but one snapshot stands out from the rest: the Eagle Nebula’s Pillars of Creation. In 1995 Hubble’s iconic image revealed never-before-seen details in the giant columns and now the telescope is kickstarting its 25th year in orbit with an even clearer, and more stunning, image of these beautiful structures.

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7
Jan 15

Where Did All the Stars Go?

Source: ESO Photo Release eso1501

The dark nebula LDN 483The Wide Field Imager (WFI) on the MPG/ESO 2.2-metre telescope at the
La Silla Observatory in Chile snapped this image of the dark nebula LDN 483.
Image credit: ESO

Some of the stars appear to be missing in this intriguing new ESO image. But the black gap in this glitteringly beautiful starfield is not really a gap, but rather a region of space clogged with gas and dust. This dark cloud is called LDN 483 — for Lynds Dark Nebula 483. Such clouds are the birthplaces of future stars. The Wide Field Imager, an instrument mounted on the MPG/ESO 2.2-metre telescope at ESO's La Silla Observatory in Chile, captured this image of LDN 483 and its surroundings. (learn more)

 

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6
Jan 15

Gemini Planet Imager finds disk of dust from asteroids or comets left behind by planet formation

Source: Gemini Planet Imager

hr4796aFirst light image of thedisk around the young star HR4796A.  Image credit: Marshall Perrin (Space Telescope Science Institute) / the GPI Team.On the left: all radiation; on the right: polarized radiation.

This year marks the 20th anniversary of 51 Peg b, the first exoplanet detected around a Sun-like star. And although the number of sheer detections in the years since have been remarkable, it’s also remarkable how little we still know about these alien worlds, save for their distances from their host stars, their radii, and sometimes their masses.

But the ability to directly image these worlds provides the opportunity to change all that. “It’s the tip of the iceberg,” said Marshall Perrin from the Space Telescope Science Institute in a press conference at the American Astronomical Society’s meeting earlier today. “In the long run, we think that imaging offers perhaps the best path to characterizing rocky planets on Earth-like orbits.”

Perrin highlighted two intriguing results from the Gemini Planet Imager (GPI), an instrument designed not only to resolve the dim light of an exoplanet, but also analyze a planet’s atmospheric temperature and composition.

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5
Jan 15

How did we find the distance to the Sun?

Source: Universe Today

Sun-CME-NASA-1024x576Credit: NASA Goddard Space Flight Center

How far is the Sun? It seems as if one could hardly ask a more straightforward question. Yet this very inquiry bedeviled astronomers for more than two thousand years.

Certainly it’s a question of nearly unrivaled importance, overshadowed in history perhaps only by the search for the size and mass of the Earth. Known today as the astronomical unit, the distance serves as our reference within the solar system and the baseline for measuring all distances in the Universe.

Thinkers in Ancient Greece were among the first to try and construct a comprehensive model of the cosmos. With nothing but naked-eye observations, a few things could be worked out. The Moon loomed large in the sky so it was probably pretty close. Solar eclipses revealed that the Moon and Sun were almost exactly the same angular size, but the Sun was so much brighter that perhaps it was larger but farther away (this coincidence regarding the apparent size of the Sun and Moon has been of almost indescribable importance in advancing astronomy). The rest of the planets appeared no larger than the stars, yet seemed to move more rapidly; they were likely at some intermediate distance. But, could we do any better than these vague descriptions? With the invention of geometry, the answer became a resounding yes.(...)
Read the rest of How Did We Find the Distance to the Sun?

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4
Jan 15

Herschel discovers galaxy cluster core ablaze with star formation.

Source: ESA/Herschel

Herschel_Chandra_Subaru_xdcpj004_295Galaxy Cluster Fireworks.
Credit: X-ray: NASA/CXC/INAF/P.Tozzi, et al; Optical: NAOJ/Subaru and ESO/VLT; Infrared: ESA/Herschel/J. Santos, et al.

In the present universe galaxy clusters cores are typically populated by massive "red and dead" galaxies. At some point in cosmic history, however, these galaxies must have formed the bulk of their stars. Now Herschel has observed a massive cluster labelled XDCP0044 at redshift z=1.58 (lookback time ~9.5 Gyr) where galaxies in the cluster core exhibit strikingly high amounts of star formation, the first time this has been seen in a massive cluster (Santos et al. 2015).

For more information on this discovery and figure captions see the ESA Herschel SciTech web release.

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3
Jan 15

XMM-Newton spots monster black hole hidden in tiny galaxy

Source: ESA/XMM-Newton

XMM-Newton_J1329+3234_2-10keV_bar_275X-ray emission from dwarf galaxy J1329+3234.
Image credit: ESA/XMM-Newton/N. Secrest, et al. (2015)

First impressions can be deceptive – astronomers have used ESA's X-ray satellite XMM-Newton to find a massive black hole hungrily feeding within a tiny dwarf galaxy, despite there being no hint of this black hole from optical observations.(learn more)

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1
Jan 15

New insight on terrestrial Gamma-ray flashes

Source: NASA Science News

New research shows that terrestrial gamma-ray flashes arise from an unexpected diversity of thunderstorms storms and may be more common than previously thought.(learn more)

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31
Dec 14

Dawn spacecraft begins approach to dwarf planet Ceres

Source: NASA Science News

NASA's ion-propelled Dawn spacecraft has begun its approach to Ceres, a Texas-sized dwarf planet never before visited by a spacecraft. The next couple of months promise continually improving views of Ceres, prior to Dawn's arrival. By the end of January, the spacecraft's images and other data will be the best ever taken of the dwarf planet. (learn more)


Learn about ion engines by playing the video above.

 

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21
Dec 14

Rosetta to Swoop Down on Comet in February

Source: NASA Science News

The European Space Agency’s orbiting Rosetta spacecraft is expected to come within four miles of the surface of comet 67P/Churyumov–Gerasimenko in February 2015. The low flyby will be an opportunity for Rosetta to obtain imagery with a resolution of a few inches per pixel. (learn more)

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19
Dec 14

Public Contest to Name Craters on Planet Mercury

Source: IAU Newsletter

iau1407a

The MESSENGER Education and Public Outreach (EPO) Team is launching a competition this week to name five impact craters on Mercury in conjunction with the IAU. (learn more)

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19
Dec 14

New evidence for a Mars water reservoir

Source: NASA Science News

splash1

NASA and an international team of planetary scientists have found evidence in meteorites on Earth that indicates Mars has a distinct and global reservoir of water or ice near its surface.(learn more)

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18
Dec 14

Venus Express goes gently into the night

Source: ESA

Venus_Express_aerobraking_large

ESA's Venus Express has ended its eight-year mission after far exceeding its planned life. The spacecraft exhausted its propellant during a series of thruster burns to raise its orbit following the low-altitude aerobraking earlier this year.

Since its arrival at Venus in 2006, Venus Express had been on an elliptical 24 hour orbit, travelling 66 000 km above the south pole at its furthest point and to within 200 km over the north pole on its closest approach, conducting a detailed study of the planet and its atmosphere.

However, after eight years in orbit and with propellant for its propulsion system running low, Venus Express was tasked in mid-2014 with a daring aerobraking campaign, during which it dipped progressively lower into the atmosphere on its closest approaches to the planet.

Normally, the spacecraft would perform routine thruster burns to ensure that it did not come too close to Venus and risk being lost in the atmosphere. But this unique adventure was aimed at achieving the opposite, namely reducing the altitude and allowing an exploration of previously uncharted regions of the atmosphere.

The campaign also provided important experience for future missions - aerobraking can be used to enter orbit around planets with atmospheres without having to carry quite so much propellant.

Between May and June 2014, the lowest point of the orbit was gradually reduced to about 130-135 km, with the core part of the aerobraking campaign lasting from 18 June to 11 July.

After this month of 'surfing' in and out of the atmosphere at low altitudes, the lowest point of the orbit was raised again through a series of 15 small thruster burns, such that by 26 July it was back up to about 460 km, yielding an orbital period of just over 22 hours.

The mission then continued in a reduced science phase, as the closest approach of the spacecraft to Venus steadily decreased again naturally under gravity.

Under the assumption that there was some propellant still remaining, a decision was taken to correct this natural decay with a new series of raising manoeuvres during 23-30 November, in an attempt to prolong the mission into 2015.

However, full contact with Venus Express was lost on 28 November. Since then the telemetry and telecommand links had been partially re-established, but they were very unstable and only limited information could be retrieved.

"The available information provides evidence of the spacecraft losing attitude control most likely due to thrust problems during the raising manoeuvres," says Patrick Martin, ESA's Venus Express mission manager.

"It seems likely, therefore, that Venus Express exhausted its remaining propellant about half way through the planned manoeuvres last month."

Unlike cars and aircraft, spacecraft are not equipped with fuel gauges, so the time of propellant exhaustion for any satellite - especially after such a long time in space - is difficult to predict. The end could not be predicted but was not completely unexpected either.

Without propellant, however, it is no longer possible to control the attitude and orient Venus Express towards Earth to maintain communications. It is also impossible to raise the altitude further, meaning that the spacecraft will naturally sink deeper into the atmosphere over the coming weeks.

"After over eight years in orbit around Venus, we knew that our spacecraft was running on fumes," says Adam Williams, ESA's acting Venus Express spacecraft operations manager.

"It was to be expected that the remaining propellant would be exhausted during this period, but we are pleased to have been pushing the boundaries right down to the last drop."

"During its mission at Venus, the spacecraft provided a comprehensive study of the planet's ionosphere and atmosphere, and has enabled us to draw important conclusions about its surface," says Håkan Svedhem, ESA's Venus Express project scientist.

Venus has a surface temperature of over 450°C, far hotter than a normal kitchen oven, and its atmosphere is an extremely dense, choking mixture of noxious gases.

One highlight from the mission is the tantalising hint that the planet may well be still geologically active today. One study found numerous lava flows that must have been created no more than 2.5 million years ago - just yesterday on geological timescales - and possibly even much less than that.

Indeed, measurements of sulphur dioxide in the upper atmosphere have shown large variations over the course of the mission. Although peculiarities in the atmospheric circulation may produce a similar result, it is the most convincing argument to date of active volcanism.

Even though the conditions on the surface of Venus are extremely inhospitable today, a survey of the amount of hydrogen and deuterium in the atmosphere suggests that Venus once had a lot of water in the atmosphere, which is now mostly gone, and possibly even oceans of water like Earth's.

Also just like Earth, the planet continues losing parts of its upper atmosphere to space: Venus Express measured twice as many hydrogen atoms escaping out of the atmosphere as oxygen atoms. Because water is made of two hydrogen atoms and one oxygen atom, the observed escape indicates that water is being broken up in the atmosphere.

Studies of the planet's 'super-rotating' atmosphere - it whips around the planet in only four Earth-days, much faster than the 243 days the planet takes to complete one rotation about its axis - also turned up some intriguing surprises. When studying the winds, by tracking clouds in images, average wind speeds were found to have increased from roughly 300 km/h to 400 km/h over a period of six Earth years.

At the same time, a separate study found that the rotation of the planet had slowed by 6.5 minutes since NASA's Magellan measured it before completing its five-year mission at Venus 20 years ago. However, it remains unknown if there is a direct relationship between the increasing wind speeds and the slowing rotation.

"While the science collection phase of the mission is now complete, the data will keep the scientific community busy for many years to come," adds Håkan.

"Venus Express has been part of our family of spacecraft in orbit since it was launched in 2005," says Paolo Ferri, Head of ESA Mission Operations.

"It has been an exciting experience to operate this marvellous spacecraft in the Venus environment. The scientific success of the mission is a great reward for the work done by the operations teams and makes us more proud than sad in this moment of farewell."

"While we are sad that this mission is ended, we are nevertheless happy to reflect on the great success of Venus Express as part of ESA's planetary science programme and are confident that its data will remain important legacy for quite some time to come," says Martin Kessler, Head of ESA Science Operations.

"The mission has continued for much longer than its planned lifetime and it will now soon go out in a blaze of glory."

"Venus Express was an important element of the scientific programme of ESA and, even though mission operations are ending, the planetary science community worldwide will continue to benefit from more than eight years of Venus Express data and major discoveries which foster the knowledge of terrestrial planets and their evolution," says Alvaro Giménez, ESA's Director of Science and Robotic Exploration.

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17
Dec 14

Curiosity Detects Methane Spike on Mars

Source: NASA Science News

splash5b

NASA's Mars Curiosity rover has measured a tenfold spike in methane, an organic chemical, in the atmosphere around it and detected other organic molecules in a rock-powder sample collected by the robotic laboratory’s drill. (learn more)

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