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Astronomy news – skyatnightmagazine

Astronomy news – skyatnightmagazine


Astronomy news – skyatnightmagazine
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Has lockdown affected light pollution?
https://www.skyatnightmagazine.com/news/does-coronavirus-lockdown-mean-clearer-skies-for-astronomers/ Thu, 21 Jan 2021 11:54:17 +0000



https://www.skyatnightmagazine.com/?p=46628


Many of us dream of a night sky over a city unaffected by light pollution. While this might seem an impossibility, one outcome of COVID-19 and national lockdowns during the pandemic has been a ‘natural experiment’ on the relationship between human activity and our effect on the environment.

Satellite observations revealed a drop in atmospheric levels of nitrogen dioxide (a major air pollutant released by the burning of fossil fuels) over cities and industrial centres, and levels of ‘PM10’ sooty particles in the air were also greatly reduced.

But what effect are the restrictions around coronavirus having on light pollution?

The main source of information on global night-time light emissions is the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard the Suomi NPP satellite.

More:

  • What’s the best telescope to use under light pollution?
  • How to capture astrophotos from a light-polluted city
Earth at night, as imaged by the Visible Infrared Imaging Radiometer Suite. Credit: Joshua Stevens, Miguel Román, NASA Goddard Space Flight Center.
Earth at night, as imaged by the Visible Infrared Imaging Radiometer Suite. Credit: Joshua Stevens, Miguel Román, NASA Goddard Space Flight Center.

But the problem with using this dataset to compare light pollution before and during the pandemic is that the images are taken by the satellite passing overhead at 1:30am local time, long after most people have already gone to sleep and lights are turned off.

As Máximo Bustamante-Calabria at the Astrophysical Institute of Andalucía explains, the key to uncovering the effects of human activity is in combining this satellite imagery with local ground measurements of sky brightness.

He and his team have collected this data for the city of Granada in Spain, including both before the pandemic and during the lockdown from mid-March to the end of May 2020.

Light pollution above the cities of Toulouse and Tarbes, France. Credit: Christophe Lehenaff / Getty Images
Light pollution above the cities of Toulouse and Tarbes, France. Credit: Christophe Lehenaff / Getty Images

As many amateur astronomers know, the problem of light pollution on the night skies is not just the amount of artificial lighting, but also the haze of PM10 particles in air pollution reflecting that glow back towards the ground.

So Bustamante-Calabria and his team had to first disentangle the relationship between the lower levels of particle pollution in the air scattering light, and any decrease in the amount of artificial lighting during the pandemic.

When they allowed for these variations, the data revealed that during lockdown the overall light output of the city had decreased by around 20%.

The drop is even more pronounced in the blue end of the light spectrum, where the team measured a 45% decrease in sky brightness during the lockdown.

This is due to the reduction in vehicle headlights and private lighting, as well as the ornamental illumination of city monuments.

At times, lockdown has meant a dramatic decrease in rush hour traffic, leading to fewer headlights in towns at cities during darker months. Credit: Tim Graham / Getty Images
At times, lockdown has meant a dramatic decrease in rush hour traffic, leading to fewer headlights in towns at cities during darker months. Credit: Tim Graham / Getty Images

Nowadays, these are usually metal halide or LED lamps that produce a blue-white light, rather than the yellowy colour of sodium lamps (for more on this, read our guide to the best lighting to minimise light pollution).

Most of these lights are turned off by the early hours, however, and so are missed by the satellite imagery. VIIRS data doesn’t record any significant difference in the light emission of cities before and during lockdown.

Given that outdoor activity decreased by up to 90% during lockdown, Bustamante-Calabria concludes that the late-night emissions of the city are dominated by permanent lighting that doesn’t respond to the actual behaviour of its citizens.

This, he argues, is a clear waste of energy and resources, as well as being a source of frustration for many amateur astronomers.

What does ESA data tell us about lockdown light pollution?

Words: Iain Todd

According to new satellite data from the European Space Agency (ESA), one of the many impacts of the COVID-19 outbreak has been a drop in air pollution.

ESA’s Copernicus Sentinel-5P satellite has been mapping air pollution across Europe and China, and the data shows a reduction in concentrations of nitrogen dioxide – such as that released by industry, vehicles and air travel – that coincide with lockdown measures imposed by governments across the world.

ESA satellite images below represent concentrations of nitrogen dioxide from 14 to 25 March 2020, compared to average monthly concentrations from 2019.

Images from the Copernicus Sentinel-5P satellite show average nitrogen dioxide concentrations from 14 to 25 March 2020, compared to the monthly average from 2019. Credit: KNMI/ESA
Images from the Copernicus Sentinel-5P satellite show average nitrogen dioxide concentrations over Italy from 14 to 25 March 2020, compared to the monthly average from 2019. Credit: KNMI/ESA

“The nitrogen dioxide concentrations vary from day to day due to changes in the weather,” says Henk Eskes, a scientist from the Royal Netherlands Meteorological Institute (KNMI), explaining why that specific date range was chosen. “Conclusions cannot be drawn based on just one day of data alone.

“By combining data for a specific period of time, 10 days in this case, the meteorological variability partly averages out and we begin to see the impact of changes due to human activity.”

The Copernicus data could mean clearer skies for astronomers, as a reduction in nitrogen dioxide points to a correlative reduction in heavy industry, traffic and, perhaps most notably for astronomers and astrophotographers, less air traffic leaving trails across the sky.

Copernicus Sentinel-5P images showing average nitrogen dioxide concentrations over France for the same period. Credit: contains modified Copernicus Sentinel data (2019-20), processed by KNMI/ESA
Copernicus Sentinel-5P images showing average nitrogen dioxide concentrations over France for the same period. Credit: contains modified Copernicus Sentinel data (2019-20), processed by KNMI/ESA

Lockdown could also mean a reduction in light pollution from towns and cities, as office buildings close, evening traffic jams lessen and large-scale gatherings that would normally require extensive illumination are cancelled.

But while the effects of the lockdown on air pollution are clear, it remains to be confirmed whether astronomers are truly seeing a notable benefit.

Stargazing aside, ESA’s satellites continue to monitor air pollution levels across Europe and the rest of the world, providing even more data into the effects of the coronavirus shutdown on air quality.

“The long-term cooperation between ESA and KNMI proves very valuable and shows the importance of complementary analyses by different partner organisations,” says ESA’s Director of Earth Observation Programmes, Josef Aschbacher.

“As we can see, the Copernicus Sentinel-5P satellite is the best satellite equipped to monitor nitrogen dioxide concentrations on a global scale.”

Keep up to date by with air pollution monitoring via ESA’s dedicated Air Pollution website. And if you have noticed a change in observing conditions, let us know by contacting us at contactus@skyatnightmagazine.com.

Iain Todd is BBC Sky at Night Magazine’s Staff Writer.

Prof Lewis Dartnell is an astrobiologist at the University of Westminster.

Lewis Dartnell was reading Effects of the COVID-19 lockdown on urban light emissions: ground and satellite comparison by Máximo Bustamante-Calabria. Read it online at arxiv.org.

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Strange dark storms spotted on planet Neptune
https://www.skyatnightmagazine.com/space-science/neptune-strange-dark-storms/ Sat, 19 Dec 2020 08:10:21 +0000




https://www.skyatnightmagazine.com/?p=57036


A dark storm spotted on Neptune by the Hubble Space Telescope. Credit: NASA, ESA, STScI, M.H. Wong (University of California, Berkeley) and L.A. Sromovsky and P.M. Fry (University of Wisconsin-Madison)

A strange dark spot has been observed drifting across the northern hemisphere of Neptune by astronomers using the Hubble Space Telescope.

The spot, which indicates the presence of a storm on the outmost planet of the Solar System, is wider than the Atlantic Ocean and was first observed by astronomers in 2018.

A year later, Hubble images showed that it had begun moving south towards Neptune‘s equator, where normally such storms would vanish.

However, images seen in August 2020 showed the dark spot returning towards the north: something astronomers did not expect to see.

Another smaller spot was also seen appearing temporarily near the larger storm in January 2020.
This may have been a piece of the vortex that broke off and drifted away from the larger storm.

Neptune’s stormy atmosphere

Neptune's Great Dark Spot as seen by the Voyager 2 spacecraft. Credit: NASA/JPL
Neptune’s Great Dark Spot as seen by the Voyager 2 spacecraft. Credit: NASA/JPL

Dark storms on Neptune are by no means unusual. When the Voyager 2 spacecraft flew by Neptune in 1989, it revealed Neptune’s tempestuous atmosphere for the first time.

Images from Voyager 2 showed a Great Dark Spot reminiscent of the famous Great Red Spot on Jupiter.

Then the launch of the Hubble Space Telescope gave astronomers a new means to observe these spots and watch their development over time.

“We are excited about these observations because this smaller dark fragment is potentially part of the dark spot’s disruption process,” says Michael H. Wong of the University of California, Berkeley.

“This is a process that’s never been observed. We have seen some other dark spots fading away and they’re gone, but we’ve never seen anything disrupt, even though it’s predicted in computer simulations.”

Image stats

Observatory Hubble Space Telescope

Release date 16 December 2020

Image credit NASA, ESA, STScI, M.H. Wong (University of California, Berkeley) and L.A. Sromovsky and P.M. Fry (University of Wisconsin-Madison)

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UK parliamentary group calls for dark sky legislation
https://www.skyatnightmagazine.com/news/uk-parliamentary-group-seeks-views-on-dark-sky-preservation/ Wed, 09 Dec 2020 14:15:44 +0000


https://www.skyatnightmagazine.com/?p=52397


An all-parliamentary group that’s seeking to protect the UK’s dark skies has called on the government to act urgently to cut light pollution and protect the night skies above Britain.

The demand follows a call in August 2020 by the group, the All-Party Parliamentary Group (APPG) for Dark Skies, seeking proposals on the subject of light pollution and night-sky preservation.

Earlier in 2020 a report said 61% of people in the UK live under ‘severe’ light pollution.

The glare of light pollution can be a menace for amateur astronomers. Credit: Steve Marsh
The glare of light pollution can be a menace for amateur astronomers. Credit: Steve Marsh

Light pollution is the term given to the detrimental effect of artificial lighting on our view of the night sky, as astronomical phenomena such as stars, constellations, planets and the Milky Way become more difficult to see under the glare of light from towns and cities.

Bodies such as the International Dark Sky Association and the UK-focussed Dark Sky Discovery, for example, help identify and preserve regions of low light pollution where views of the night sky are protected.

This latest report from the APPG for Dark Skies says there are “big gaps” in the current legal framework and planning permission processes in the UK in terms of regulating light pollution.

It calls for new legislation to protect the darkness of the night sky over the UK, including the creation of a statutory Commission for Dark Skies to “punish non compliance” and to empower local authorities to enforce regulations.

It also says there should be standardised brightness and colour temperature of lighting, including legal limits to the amount of blue light emitted by a luminaire.

Dunkery Beacon in Exmoor National Park is one of many places in the UK where beautiful vistas of the night sky can be seen. Credit: Keith Trueman
Dunkery Beacon in Exmoor National Park is one of many places in the UK where dark skies are protected. Could legislation be brought in to protect dark skies over towns and cities? Credit: Keith Trueman

The report says all lighting units should be sold and distributed with instructions for “the control of obtrusive light”, and suggests the implementation of ‘Dark Sky Hours’ in which some lighting could be dimmed or turned off.

The group have also called for the appointment of a designated Minister for Dark Skies and a Dark Sky Towns & Cities initiative to create voluntary ‘Dark Sky Town/City’ classifications across the UK.

Click here for the full APPG for Dark Skies policy plan.

APPG for Dark Skies co-chairs Andrew Griffith MP (left) and Astronomer Royal Martin Rees (right).
APPG for Dark Skies co-chairs Andrew Griffith MP (left) and Astronomer Royal Martin Rees (right).

The APPG for Dark Skies includes members from the Conservative Party, Labour and the Liberal Democrats, as well as representatives from the House of Lords. Its aim is to advocate for the preservation of dark skies in the UK Parliament.

The group was founded in January 2020 by co-chairs Andrew Griffith, Conservative MP for Arundel and South Downs, and Astronomer Royal Lord Martin Rees.

Its purpose is to gather information on the key threats to dark-sky preservation in the UK and identify solutions, such as changes to planning policy or the adoption of dark-sky friendly lighting.

As well as focussing on the effects of light pollution on astronomy and stargazing, the consultation process also investigated the environmental, economic, energy and health consequences of light pollution.

For more information visit the APPG for Dark Skies website.

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Milky Way bulge imaged in survey of 250 million stars
https://www.skyatnightmagazine.com/space-science/milky-way-bulge-image-survey-250-million-stars/ Sat, 28 Nov 2020 08:30:49 +0000




https://www.skyatnightmagazine.com/?p=56329


A DECam image showing the bulge of the Milky Way: part of a survey of 250 million stars. Credit: CTIO/NOIRLab/DOE/NSF/AURA. Acknowledgment: Image processing: W. Clarkson (UM-Dearborn), C. Johnson (STScI), and M. Rich (UCLA), Travis Rector (University of Alaska Anchorage), Mahdi Zamani & Davide de Martin.

A new image of the Milky Way’s bulge reveals the centre of our home galaxy in incredible detail, and is part of a survey examining over 250 million stars in the region.

Using ultraviolet data and 450,000 individual images, astronomers have been measuring the chemical composition of tens of thousands of stars within the Milky Way’s bulge.

The survey is part of a project using the Dark Energy Camera (DECam) on the Víctor M.Blanco 4m Telescope at Cerro Tololo Inter-American Observatory (CTIO) in Chile.

CTIO is one of 5 programs hosted by the National Science Foundation’s (NSF) NOIRLab centre.

A wide-field view of the Milky Way. The box indicates the location of the region seen in the newly-released image. Credit: CTIO/NOIRLab/DOE/NSF/AURA/STScI, W. Clarkson (UM-Dearborn), C. Johnson (STScI), and M. Rich (UCLA)/E.Slawik
A wide-field view of the Milky Way. The box indicates the location of the region seen in the newly-released image. Credit: CTIO/NOIRLab/DOE/NSF/AURA/STScI, W. Clarkson (UM-Dearborn), C. Johnson (STScI), and M. Rich (UCLA)/E.Slawik

The team behind the study have been detecting ultraviolet light from stars in the bulge known as Red Clump stars, analysing over 70,000 across a region of sky 1,000 times as large as the full Moon.

So far, the survey has shown that stars near the centre of the Milky Way have a similar composition, suggesting they formed around the same time.

This was calculated by measuring the difference in stars’ brightnesses from ultraviolet to infrared wavelengths and calibrating the data with spectroscopic measurements of stars.

A region near the centre of the Milky Way galaxy covering 0.5 by 0.25 degrees, which is about twice as wide as the full Moon in the night sky. This image contains over 180,000 stars and shows a region of our galaxy about 220x100 lightyears across. It was captured by the Dark Energy Camera on the Víctor M. Blanco 4-meter Telescope. Credit: CTIO/NOIRLab/DOE/NSF/AURA/STScI, W. Clarkson (UM-Dearborn), C. Johnson (STScI), and M. Rich (UCLA)
A region near the centre of the Milky Way galaxy covering 0.5 by 0.25 degrees, which is about twice as wide as the full Moon in the night sky. This image contains over 180,000 stars and shows a region of our galaxy about 220×100 lightyears across. It was captured by the Dark Energy Camera on the Víctor M. Blanco 4-meter Telescope. Credit: CTIO/NOIRLab/DOE/NSF/AURA/STScI, W. Clarkson (UM-Dearborn), C. Johnson (STScI), and M. Rich (UCLA)

“This is exactly the strength of the Dark Energy Camera — to undertake these kinds of studies,” says Kathy Vivas, co-author and NOIRLab astronomer.

“While it was originally aimed at the study of the distant Universe to measure its expansion, DECam has proven to be a powerful instrument to study our Milky Way as well.”

“Many other spiral galaxies look like the Milky Way and have similar bulges, so if we can understand how the Milky Way formed its bulge then we’ll have a good idea of how the other galaxies did too,” says study co-leader Christian Johnson of Space Telescope Science Institute.

The Víctor M. Blanco 4m Telescope and the Dark Energy Camera (black paint) at the Cerro Tololo Inter-American Observatory (CTIO) in Chile. Credit: DOE/LBNL/DECam/R. Hahn/CTIO/NOIRLab/NSF/AURA
The Víctor M. Blanco 4m Telescope and the Dark Energy Camera (black paint) at the Cerro Tololo Inter-American Observatory (CTIO) in Chile. Credit: DOE/LBNL/DECam/R. Hahn/CTIO/NOIRLab/NSF/AURA

Image stats

  • Observatory Víctor M. Blanco 4-meter Telescope
  • Release date 27 October 2020
  • Image credit CTIO/NOIRLab/DOE/NSF/AURA. Acknowledgment: Image processing: W. Clarkson (UM-Dearborn), C. Johnson (STScI), and M. Rich (UCLA), Travis Rector (University of Alaska Anchorage), Mahdi Zamani & Davide de Martin.
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Astronomers capture shadow of dust disc around supermassive black hole
https://www.skyatnightmagazine.com/news/shadow-dust-disc-around-supermassive-black-hole/ Sat, 21 Nov 2020 08:10:28 +0000



https://www.skyatnightmagazine.com/?p=56114


Cone-shaped shadows emanating from the bright centre of galaxy IC 5063 could be cast by the dusty ring surrounding the supermassive black hole at its centre. Credit: NASA, ESA, STScI and W.P. Maksym (CfA)

Astronomers using the Hubble Space Telescope may have captured an image of shadows cast by a dusty ring surrounding a supermassive black hole at the centre of a galaxy.

An image released by the team shows the centre of nearby active galaxy IC 5063, where bright rays of light and dark shadows are seen emanating from within.

In particular, a two-pronged shadow appears to be emerging from the bright galactic centre – seen below and above the galaxy in the image – that could be cast by the dust ring.

The astronomers behind the study are led by Peter Maksym of the Center for Astrophysics at Harvard & Smithsonian in the US.

Studying the galaxy, the team have managed to trace the projection of light rays back into the galactic core, where resides a supermassive black hole.

Discover more:

  • Podcast: What is a black hole?
  • How do black holes form?
  • Supermassive black hole imaged for the first time
An artist's impression of the dusty disc surrounding the black hole at the centre of galaxy IC 5063. The disc is casting its shadows into space, while bright rays pass through gaps in the material. Credit: NASA, ESA, and Z. Levy (STScI)
An artist’s impression of the dusty disc surrounding the black hole at the centre of galaxy IC 5063. The disc is casting shadows into space, while bright rays pass through gaps in the material. Credit: NASA, ESA, and Z. Levy (STScI)

Black holes are dense regions of space from which not even light can escape, and astronomers infer that most galaxies, including our own Milky Way, have a supermassive black hole at their centre.

IC 5063 is no exception, and like other galaxies its supermassive black hole can be detected as streams of light energy generated as cosmic matter falls inwards.

But what can also be seen in this new Hubble image are displays of shadows and light stretching across at least 36,000 lightyears. The team believe these could be cast by a ring of dusty material surrounding the black hole.

Sunlight filters through clouds creating crepuscular rays, also known as 'God rays', in this image captured at Grand Tetons National Park in the US in 2017. Similar effects could be occurring at galaxy IC 5063 where light is partially blocked by the dusty disc surrounding the supermassive black hole at its centre. Credit: Z. Levay The photographer was facing east—away from the iconic Grand Teton Mountains—when he snapped this image in 2017. The light rays are formed by sunlight piercing the clouds. The darker regions represent the clouds casting shadows where sunlight could not pass through. This interplay of light and shadow is similar to the bright rays and dark shadows stretching across the nearby active galaxy IC 5063. In that case, a monster black hole in the galaxy’s core is producing a gusher of light from superheated infalling gas. Most of the light is penetrating the dust ring encircling the black hole, creating the bright rays. However, some light hits dense patches in the ring, casting the ring’s shadow into space.
Sunlight filters through clouds creating crepuscular rays in this image captured at Grand Tetons National Park, US in 2017. Similar effects could be occurring at galaxy IC 5063 where light is partially blocked by a dusty disc surrounding the supermassive black hole at its centre. Credit: Z. Levay

This dusty disc only blocks some of the light, however, allowing rays of light to beam outwards, generating dark cone-shaped rays similar to those that can be seen on Earth as sunlight passes through gaps in clouds (see image above).

“It’s a really cool effect that I don’t think we’ve seen before in images, although it has been hypothesised,” says Maksym.

“Scientifically, it’s showing us something that is hard – usually impossible – to see directly. We know this phenomenon should happen, but in this case, we can see the effects throughout the galaxy.

“Knowing more about the geometry of the torus will have implications for anybody trying to understand the behaviour of supermassive black holes and their environments.”

Image stats

  • Observatory Hubble Space Telescope
  • Release date 19 November 2020
  • Image credit NASA, ESA, STScI and W.P. Maksym (CfA)

Read more about this story via the Hubble Space Telescope website.

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Arecibo Telescope under threat following structural damage
https://www.skyatnightmagazine.com/space-science/arecibo-telescope/ Fri, 20 Nov 2020 09:50:30 +0000


https://www.skyatnightmagazine.com/?p=56095


The world-famous Arecibo Observatory 305m radio telescope is under threat of being decommissioned after 57 years of observing the Universe, according to the National Science Foundation.

The news follows a review of the Arecibo structure that found it could not be stabilised without risking the safety of construction workers at the facility.

The Arecibo Observatory, located in Puerto Rico, consists of a 305m-wide radio dish with a 900-ton platform hanging 450 feet above ground, and suspended by cables connected to 3 towers.

Engineers at the site have been assessing the integrity and safety of the structure since one of its support cables detached on 10 August 2020, leaving a 100-foot hole in the dish below.

A view under the dish at the Arecibo Observatory. Credit: NSF / University of Central Florida
A view under the dish at the Arecibo Observatory. Credit: NSF / University of Central Florida

The University of Central Florida, which manages the Arecibo Observatory, was authorised by NSF to remedy the fault.

However, while awaiting the delivery of 2 replacement auxiliary cables and 2 temporary cables that would have stabilised the structure, on 6 November 2020 a main cable broke on the same tower. Engineers then concluded that the existing cables were weaker than originally thought.

The decommissioning schedule at Arecibo will focus only on the 305m telescope itself and will preserve other parts of the observatory, say NSF.

Part of the decommissioning plan is to retain remaining sections of the Arecibo facility and preserve them for future research and educational outreach.

It will also involve the use of drones to conduct a photographic survey of the site, so that engineers can discern whether more of the site may be preserved based on new evidence.

Once the decommissioning process is complete, NSF officials say they intend to restore operations at other parts of the observatory, such as the Arecibo Observatory LIDAR (Light Detection and Ranging) facility, the visitor centre and the Culebra facility, which analyses cloud cover and precipitation.

The Arecibo Observatory visitor centre is one facility that will remain open, say NSF. Credit: NSF / University of Central Florida
The Arecibo Observatory visitor centre is one facility that will remain open, say NSF. Credit: NSF / University of Central Florida

Arecibo Observatory’s legacy

The Arecibo Observatory may be most well-known to the general public due to its appearance in the 1995 James Bond film Goldeneye, starring Pierce Brosnan as 007, but for astronomers it is a prolific instrument for radio astronomy that’s been revealing the secrets of the cosmos for decades, studying a range of objects including planets, comets and asteroids.

Its radio vision enables it to peer beyond what can be seen by the naked eye, through interstellar cosmic dust and into far corners of the Universe to get a closer look at deep-sky objects such as pulsars, quasars and galaxies.

Arecibo has also conducted studies of the planets in our Solar System, collecting data on Mercury, Venus, Saturn’s rings and Jupiter’s moons.

Arecibo Observatory's suspended platforms became world famous following their appearance in the film Goldeneye. Credit: NSF / University of Central Florida
Arecibo Observatory’s suspended platforms became world famous following their appearance in the film Goldeneye. Credit: NSF / University of Central Florida

“Over its lifetime, Arecibo Observatory has helped transform our understanding of the ionosphere, showing us how density, composition and other factors interact to shape this critical region where Earth’s atmosphere meets space,”  says Michael Wiltberger, head of NSF’s Geospace Section.

“While I am disappointed by the loss of investigative capabilities, I believe this process is a necessary step to preserve the research community’s ability to use Arecibo Observatory’s other assets and hopefully ensure that important work can continue at the facility.”

Images of near-Earth asteroid 3200 Phaethon captured by Arecibo Observatory on 17 December 2017. Credit: Arecibo Observatory/NASA/NSF.
Images of near-Earth asteroid 3200 Phaethon captured by Arecibo Observatory on 17 December 2017. Credit: Arecibo Observatory/NASA/NSF.

“Leadership at Arecibo Observatory and UCF did a commendable job addressing this situation, acting quickly and pursuing every possible option to save this incredible instrument,” says Ralph Gaume, director of NSF’s Division of Astronomical Sciences.

“Until these assessments came in, our question was not if the observatory should be repaired but how. But in the end, a preponderance of data showed that we simply could not do this safely. And that is a line we cannot cross.”

For more information, visit the National Science Foundation website or the Arecibo Observatory website. You can also keep up to date with this story by following both on Twitter, at @NSF and @NAICobservatory.

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Jupiter, Mars, Saturn imaged as work restarts at La Silla Observatory
https://www.skyatnightmagazine.com/space-science/jupiter-mars-saturn-image-la-silla-observatory/ Sat, 07 Nov 2020 08:10:08 +0000



https://www.skyatnightmagazine.com/?p=55775


Jupiter, Mars and Saturn imaged at ESO's La Silla Observatory in the Atacama desert. Credit: ESO

This brand new image of Jupiter, Mars and Saturn was captured at the European Southern Observatory’s La Silla Observatory in the Chilean Atacama desert as part of a restart of science operations at the facility.

Observations had taken a pause due to the COVID-19 pandemic, but towards the end of October 2020 astronomers were raring to go as restrictions eased, and captured this incredible montage of the Solar System’s most iconic planets.

Work has recommenced at the New Technology Telescope (NTT) at ESO's La Silla observation site. Credit: ESO
Work has recommenced at the New Technology Telescope (NTT) at ESO’s La Silla observation site. Credit: ESO

Jupiter, Mars and Saturn were the 3 brightest planets in the sky the night the image was captured, and the red, orange and yellow hues of the trio were achieved by combining separate images produced using 5 different filters.

The relative sizes of the planets are proportional to the angular size of the planets in the sky. Mars was at opposition when the image was taken.

Work at La Silla continues under strict health and safety measures due to the ongoing pandemic that’s affecting large swathes of the world, but the recommencement of observations is a positive sign for the astronomical community at ESO.

Image stats

Observatory New Technology Telescope, La Silla Observatory

Release date 26 October 2020

Image credit ESO

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Philae’s second comet landing site found after 6 years
https://www.skyatnightmagazine.com/news/philaes-second-comet-landing-site-found/ Wed, 28 Oct 2020 17:44:01 +0000





https://www.skyatnightmagazine.com/?p=55267


The second touchdown site of ESA’s comet landing spacecraft, Philae, has been located after six years of searching.

Philae made its way from the Rosetta orbiter to the surface of comet 67P/Churyumov-Gerasimenko back on 12 November 2014 to land not just once, but three times, after bouncing on its initial touch down.

While the sites of the first and final contacts were found within a few months, the location of the second bounce has remained elusive.

For the last six years, Laurence O’Rourke – an ESA scientist who played a leading role in finding Philae’s final landing site back in 2014 – has been hunting down this secondary landing site.

“Philae had left us with one final mystery waiting to be solved,” says O’Rourke. “It was important to find the touchdown site because sensors on Philae indicated that it had dug into the surface, most likely exposing the primitive ice hidden underneath, which would give us invaluable access to billions-of-years-old ice.”

Philae touches down on comet
ESA’s Philae lander had a bumpy start in life, ending up 1km away from its intended landing site in the shadow of a cliff.
ESA

O’Rourke and his team looked for the landing site in high resolution images from Rosetta’s OSIRIS camera, but their search was aided by a more unexpected instrument, Philae’s magnetometer boom, ROMAP.

The boom arm sticks out from Philae by 48cm and when it struck the surface of the comet it’s physical shaking caused spikes in ROMAP’s data, showing it was in contact with the surface for almost two minutes.

With this additional information, the search party were able to work out what sort of shape indentation they were looking for, and they soon located it in the OSIRIS images of the region.

“The shape of the boulders impacted by Philae reminded me of a skull when viewed from above, so I decided to nickname the region ‘skull-top ridge’ and to continue that theme for other features observed,” says O’Rouke.

“The right ‘eye’ of the ‘skull face’ was made by Philae’s top surface compressing the dust while the gap between the boulders is ‘skull-top crevice’, where Philae acted like a windmill to pass between them.”

Philae's second landing site appears to take on the form of a skull
Philae’s second landing site appears to take on the form of a skull
ESA

The findings also show that the surface of the comet at the second landing site is extraordinarily soft – similar to the froth on a cappuccino.

“This is a fantastic multi-instrument result that not only fills in the gaps in the story of Philae’s bouncy journey, but also informs us about the nature of the comet,” says Matt Taylor, ESA’s Rosetta project scientist.

“In particular, understanding the strength of a comet is critical for future lander missions. That the comet has such a fluffy interior is really valuable information in terms of how to design the landing mechanisms, and also for the mechanical processes that might be needed to retrieve samples.”

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NASA detects water on sunlit surface of the Moon
https://www.skyatnightmagazine.com/news/nasa-detects-water-sunlit-surface-moon/ Mon, 26 Oct 2020 16:29:59 +0000



https://www.skyatnightmagazine.com/?p=55133


NASA has announced the discovery of water on a sunlit surface of the Moon. The discovery could have major implications both for piecing together the history of the Solar System but also for future human spaceflight.

The discovery was made by NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA), and is particularly surprising because it suggests water can survive the extremities of the lunar day.

It could also mean that more water is available across the surface of the Moon.

The water was discovered in the Clavius crater (pictured at the top of this page) of the Moon’s southern hemisphere.

Previous observations of the lunar surface had detected hydrogen, but SOFIA’s infrared spectrometer was able to confirm the hydrogen detected is unique to the water molecule H20, indicating the presence of water.

NASA's SOFIA observatory is enabling astronomers to learn more about galactic winds. Credit: NASA
SOFIA is a 2.7-meter reflecting telescope housed aboard a Boeing 747SP aircraft. Credit: NASA

The water does not exist in puddles, but in concentrations of 100 to 412 parts per million. This is about the same as a 350ml bottle of water trapped in a cubic metre of soil spread across the surface of the Moon.

The Sahara desert, as a comparison, has 100 times the amount of water detected by SOFIA detected in the lunar soil.

It was already known that water exists in the darker, colder craters of the Moon, but finding water in a sunlit region suggests water could be more abundant on the Moon than thought, while the presence of water in more easily accessible regions of the Moon could have major implications for human spaceflight.

NASA scientists have suggested the water may be delivered by micrometeorites impacting the Moon and depositing the water on the lunar surface.

Or, it could have been delivered to the Moon by the solar wind, which is a stream of charged particles emanating from the Sun.

This could deliver hydrogen to the lunar surface, and a subsequent chemical reaction with oxygen-bearing minerals in the lunar soil could create hydroxyl. Radiation from micrometeorites might then transform that hydroxyl into water.

But how the water remains on the Moon is a mystery, as water on the sunlit surface of the Moon should be lost to space. It could be trapped within glass beads deposited by micrometeorite impacts, say NASA scientists.

The discovery has major implications for our understanding of the role played by water in the creation and evolution of the Solar System, but also for NASA’s Artemis program to establish a human presence on the Moon.

“Prior to the SOFIA observations, we knew there was some kind of hydration,” says Casey Honniball, lead author of the study at the University of Hawaii at Mānoa in Honolulu. “But we didn’t know how much, if any, was actually water molecules – like we drink every day – or something more like drain cleaner.

“Without a thick atmosphere, water on the sunlit lunar surface should just be lost to space, yet somehow we’re seeing it. Something is generating the water, and something must be trapping it there.”

“Water is a valuable resource, for both scientific purposes and for use by our explorers,” says Jacob Bleacher, chief exploration scientist for NASA’s Human Exploration and Operations Mission Directorate.

“If we can use the resources at the Moon, then we can carry less water and more equipment to help enable new scientific discoveries.”

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TESS satellite produces mosaic image of northern night sky
https://www.skyatnightmagazine.com/space-science/tess-satellite-mosaic-image-northern-night-sky/ Sat, 24 Oct 2020 07:22:02 +0000



https://www.skyatnightmagazine.com/?p=55056


A view of the northern sky captured by the TESS satellite. Credit: NASA/MIT/TESS and Ethan Kruse (USRA)

This view of the northern hemisphere sky is a mosaic produced using a total of 208 individual images captured by NASA’s exoplanet-hunting TESS telescope.

TESS, or the Transiting Exoplanet Survey Satellite, has imaged about 75% of the sky during its 2-year-long survey searching for stars orbiting distant planets, known as exoplanets.

In this new image of the northern sky can be seen the dust clouds of the Milky Way (on the left) and our neighbouring galaxy the Andromeda Galaxy (as an oval, centre left).

At the time of writing, TESS has discovered 74 exoplanets, and there are still around 1,200 additional exoplanet candidates detected by the spacecraft that have yet to be confirmed. Over 600 of these are in the northern sky.

TESS’s survey of the night sky is strictly methodical, as you might expect. It splits each celestial hemisphere into 13 regions, each of which is imaged for around a month using four cameras carrying a total of 16 CCD cameras.

The gaps in the image panels are a result of astronomers’ desire to have TESS’s cameras diverted further north in order to lessen the impact of scattered light from Earth and the Moon.

TESS is now due to spend another year imaging the southern sky, revisiting exoplanets it discovered in its first year and, mission scientists hope uncovering new worlds yet to be discovered.

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Observatory Transiting Exoplanet Survey Satellite

Release date 5 October 2020

Image credit NASA/MIT/TESS and Ethan Kruse (USRA)

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