Tag: Astronomy

Space Monday: beautiful Pluto, icy Enceladus, and jetting into space

Posted on by Inara Pey

new-horizonIn September I reported on images captured by the New Horizons space probe of the night side of Pluto, backlit by the distant Sun. In a follow-up to those images, the New Horizons team has released stunning high-resolution images captured by the probe shortly after passing the point of closest approach to Pluto on July 14th, 2015.

The images were captured from a distance of just 18,000 km (11,000 miles) from Pluto using the Multi-spectral Visible Imaging Camera (MVIC), part of New Horizon’s Ralph suite of instruments, which were pieced together to form a magnificent view of Pluto with a resolution of some 700 metres per pixel.

The mosaic of images shows the rich complexity of both Pluto’s surface features and its atmosphere, the enhanced images clearly bringing the bands of haze in the latter into sharp relief.

An enhanced image of Pluto's night side, composed of images captured by the MVIC instrument on New Horizons on July 14th, 2015. As Pluto is "tipped over" on its axis by 120 degrees, the planet's north pole is to the right and south pole to the left
An enhanced image of Pluto’s night side, composed of images captured by the MVIC instrument on New Horizons on July 14th, 2015. As Pluto is “tipped over” on its axis by 120 degrees, the planet’s north pole is to the right and south pole to the left (image: NASA/JPL / JHUAPL / SwRI)

The clearest detail of Pluto’s surface can be seen to the right, which because the planet’s axis is tilted by 120-degrees, is the north polar region. The sheer ruggedness of the terrain can be seen here, some of the pitted hills almost looking like clouds above a distant landscape. However, the left side, and the south pole isn’t entirely without interest: caught by the glow of sunlight refracted by Pluto’s tenuous atmosphere, the rugged nature of the little world’s chaotic surface can also be seen.

Subject to enhancement, a portion of the images capturing the northern regions of Pluto  reveal even more detail, particularly within the complex layering of Pluto’s atmosphere, where the enhancements reveal it to be made up of around a dozen layers, far more than had been thought during New Horizon’s final approach to Pluto in late June. These layers are made up of tholins, soot-like organic compounds created as a result of ultraviolet radiation from the sun interacting with the upper layers of Pluto’s atmosphere. These particles, undergoing some chemical changes as they drift back down through the various layers, eventually precipitate down onto Pluto’s surface, staining it red.

An enhanced image of Pluto north polar region revealing an incredibly complex surface of hills and valleys, ice features and high mountains, while above can be seen an enhanced view of the complex atmospheric banding
An enhanced image of Pluto north polar region revealing an incredibly complex surface of hills and valleys, ice features and high mountains, while above can be seen an enhanced view of the complex atmospheric banding (image: NASA/JPL / JHUAPL / SwRI)

Cassini’s Enceladus Encounter

Cassini, NASA’s deep space probe exploring Saturn and his retinue of moons as a part of the Cassini-Huygens mission, is approaching the end of its 20-year mission. Launched in 1997, and following a 7-years transit to Saturn, Cassini has been studying the system in great detail, and delivered a tiny European lander vehicle, Huygens, to the surface of Titan, the largest moon in the solar system, and one with its own rich atmosphere, and standing bodies of liquid on its surface.

With fuel reserves set to expire in late 2017, Cassini will be ordered to fly into Saturn’s own dense atmosphere before it does so, where it will burn-up. In the meantime, however, the vehicle continues to return a marvellous wealth of data about the Saturn system, including several studies of another of the giant planet’s remarkable moons, Enceladus.

Enceladus revealed: captured on October 28th, this image reveals the icy beauty of encedaus as Cassini closes for its penultimate, and closest, approach to this tiny Moon with its hidden ocean
Enceladus revealed: captured on October 28th, this image reveals the icy beauty of the moon as Cassini closes for its penultimate, and closest, approach (image: NASA/JPL / Space Science Institute)

Like Jupiter’s moon Europa, Enceladus is a domain of ice, under which likely sits an ocean of liquid water. Shortly after arriving in orbit around Saturn, Cassini made the first of numerous flybys of the little Moon, which is just 500 km (310 mi) across, and detected the presence of a very thin atmosphere primarily made up of water vapour. In particular, the craft observed geysers erupting from the south pole, spewing water vapour, ice particles and other material into space, some of which likely contributes to Saturn’s “E” ring.

At the end of October 2015, Cassini made its penultimate flyby of Enceladus, passing over the Moon at an altitude of just 48 km (30 mi) and at a speed of some 30,000 kph (19,000 mph), diving through another of the geyser plumes in the process to measure the composition of gas and ice particles launched from the underground ocean.

A stunning images taken by Cassini following the October flyby reveals a crescent Enceladus floating above Saturn's magnificent rings
A stunning images taken by Cassini following the October flyby reveals a crescent Enceladus floating above Saturn’s magnificent rings (image: NASA/JPL / Space Science Institute)

In particular, the Cassini science team will be analysing the data returned by Cassini following the flyby to see if the sensors found any evidence of molecular hydrogen in the plumes. Doing so would help verify suspected hydrothermal activity is taking place on the floor of Enceladus’ ice-shrouded ocean which could give rise to hot environments rich in mineral and chemical deposits suitable for the development of microbial life, just as deep-ocean thermal vents here on Earth provide life-sustaining environments.

Cassini will make one more return to Enceladus on December 19th, but will pass further from the little Moon as its orbit gradually swings it around Saturn for a further and final set of encounters with giant Titan, before finally moving inwards to pass between Saturn and its rings for the first time to study Saturn’s atmosphere in detail as the mission draws to a close in 2017.

Dawn Descends Over Ceres

On October 23rd, the NASA / ESA joint mission to explore two of the solar system’s three “protoplanets” located in the asteroid belt between the orbits of Mars and Jupiter, commenced manoeuvres to lower itself to is final orbit around Ceres.

The Dawn spacecraft, which arrived at Ceres in March 2015, after a 2.5 year transit flight from Vesta, its first destination, fired its ion engine to start reducing its orbit from 1,450 kilometres (915 miles) to just 380 km (235 mi), a manoeuvre which should see the vehicle spiral gently downwards to arrive in its new orbit in mid-December. At that time, Dawn will commence a final mapping and data-gathering mission, providing images with a resolution of 35 metres (120 ft) per pixel.

Occator crater and its brights spots images from directly overhead and a distance of 1,470 km (915 miles) by the Dawn space vehicle
Occator crater and its bright spots images from directly overhead and a distance of 1,450 km (915 miles) by the Dawn space vehicle (image: NASA / JPL / DLR)

It is hoped that this final science orbit will offer definitive data on precisely what is giving rise to a series of odd bright spots within the crater Occator on Ceres, and which appear to be related to what seems to be a small and very localised trace atmosphere within the crater. Current thinking is the bright markings are salt or ice water deposits which are being out-gassed from Ceres’ interior.

Britain’s Spaceplane Gets £80 million Investment

SABRE is the name of a radical “air-breathing” hybrid engine which has been in development by  a small British company called Reaction Engines Limited (REL) since the late 1990s. The aim is to reduce the amount of on-board oxidiser required in the rocket combustion process by allowing the engine to draw on the air around it during the initial ascent through the denser part of the Earth’s atmosphere, much like a regular jet engine uses the air around it. Only when the air becomes too thin to support combustion does the rocket engine switch over to its on-board supplies of liquid oxygen to burn with its liquid hydrogen fuel.

Ultimately, REL hope to use the SABRE engine in a single stage to orbit (SSTO) vehicle called Skylon, a fully reusable space launch vehicle, capable of operating from and to a conventional runway just like an aeroplane, and carrying up to tonnes into low Earth orbit.  However, the SABRE engine potentially has a wide range of applications, including a purely “air-breathing” variant (called Scimitar) which could be used to power aircraft within Earth’s atmosphere at speeds close to five times that of sound.

REL propose using the SABRE engine in their Skylon spaceplane capable of lifting up to 15 tonnes (cargo or 24 passengers) into orbit. however, the engine has many potential uses, hence the interest from BASE Systems and the UK government (image: REL)
REL propose using the SABRE engine in their Skylon spaceplane capable of lifting up to 15 tonnes (cargo or 24 passengers) into orbit. however, the engine has many potential uses, hence the interest from BASE Systems and the UK government (image: REL)

On Monday, November 2nd, REL announced that BAE Systems Ltd is to invest some £20.6 million (US $31.8 million) in REL in return for a 20% stake in the company, while the UK government has awarded a further £60 million (US $92.8 million). Together with recent funding from the EU, REL has now raised some £95 million (US $146.6 million)  to further develop SABRE.

Skulls in the Sky

Halloween 2015 brought with it a creepy-looking visitor which looked down on Earth as many across the world took to marking All Hallows Eve on Saturday, October 31st.

The visitor in question was asteroid 2015 TB145, a lump of rock around 600 metres (1,968 feet) across. Tumbling through space, it passed by the Earth at a distance of roughly 480,000 km (300,000 miles) – slightly further from us than the orbit of the Moon,  at a speed of some 126,000 kph (78,293 mph).

Such Earth-passing asteroids are not rare, although this one was only identified on October 10th, 2015. It well be the last close passage to Earth by a very large asteroid until 2027, and its size offered scientists a unique opportunity to image it using radar.

Asteroid 2015 TB145 in an eerily skull-lik image captured by the Are
Asteroid 2015 TB145 in an eerily skull-like image captured by the Arecibo Observatory on Friday, October 30th, 2015.

On Friday, October 30th, the The Arecibo Observatory in Puerto Rico used radar mapping to capture an image of the asteroid in which it looks like a gigantic skull.  It was all an optical illusion of course, the combined result of the radio reflections from the asteroid giving rise to the grey shaded image and the effect of pareidolia, in which the human brain perceives shapes and patterns that aren’t really there; as the asteroid tumbled through space, the similarities to a human skull were quickly lost as the radar reflections changed.

Nevertheless, it was fittingly spooky for Halloween!

Discover Gale Crater

I’ve written extensively about NASA’s Curiosity rover and its explorations within Gale Crater on Mars since its arrival there in August 2012. Now NASA and the Los Angeles Times have combined to provide a virtual reality exploration of Gale Crater, which examines some of the principal features to be found there, traces the rover’s route from crater floor and up the flank of “Mount Sharp” and which allows visitors to fly over the crater or take a guided tour using simple keyboard controls.

Space Sunday: from the Sun to Charon, and the death of a planet

Posted on by Inara Pey
Astrophotographer Mia Stålnacke caught this aurora display over Kiruna, Sweden, in March 2015
Astrophotographer Mia Stålnacke caught this aurora display over Kiruna, Sweden, in March 2015

The Sun is the only star we can directly observe in detail. As such, it has been the subject of study for a long time, significantly so since the birth of the space age. As such, you’d think we know pretty much all there is to know about it; but the fact is that the Sun still has many mysteries – and surprises – of its own awaiting understanding and discovery.

One of these mysteries has been strange particle emissions rich in helium-3. These don’t form part of the more familiar coronal mass ejections (CMEs), which can have an elevated impact on Earth magnetosphere giving rising to more energetic aurorae, or with collimated X-ray flares. The cause of these helium-3 rich outbursts has until now been hard to trace because in order to be detected by the Advanced Composition Explorer (ACE) craft which is designed to study such energetic particles, they have to originate very close to the Sun’s limb, making any associated events hard to observe.

A look at the Sun’s right limb on January 26, 2010. Within the marked red square, a large-scale blast wave travels through the Sun’s atmosphere. These images were obtained with the help of NASA’s STERO A probe and show the Sun’s atmosphere in extreme ultraviolet light.
A look at the Sun’s right limb on January 26, 2010. Within the marked red square, a large-scale blast wave travels through the Sun’s atmosphere. These images were obtained with the help of NASA’s STEREO A probe and show the Sun’s atmosphere in extreme ultraviolet light.

However, on October 13th, two teams of scientists working independently of one another, but using the same data and images gathered from NASA’s STEREO solar observation vehicle and the Earth-orbiting ACE platform, announced they had pin-pointed the cause of the outbursts. They are the result of huge explosions occurring in the Sun’s atmosphere, which in turn create gigantic atmospheric shock waves in the Sun’s atmosphere which can extend over half a billion kilometres (300,000 miles) and advance at speeds of 300 km (190 mi) per second. It is believed the sheer speed of the shock waves from these explosions is sufficient to accelerate  the helium-3 (itself produced as a part of the overall fusion process in the Sun’s core), into a stream of particles thrown off into space.

While it has been confirmed the initial explosions are not related to CMEs or sunspots or other known solar phenomena, the precise reason for the explosions themselves has yet to be determined.

Charon Revealed

Images and data returned by the New Horizons space vehicle at the start of October have provided more details about Pluto’s companion, Charon, revealing it to be an even more fascinating world than had been anticipated.

Charon as revealed in the highest resolution images yet returned of that tiny world by New Hotizons (image: NASA/JPL / JHUAPL / SwRI)
Charon as revealed in the highest resolution images yet returned of that tiny world by New Horizons (image: NASA/JPL / JHUAPL / SwRI)

The images, captured in black and white by the probe’s LORRI camera, have been combined with images and data gathered by the RALPH suite of instruments to present a beautiful full-colour image of almost all of one face of Charon, as seen by New Horizons as it swept through its closest approach to both Charon and Pluto on July 14th, 2015.

Some 1,214 kilometres (753 miles) in diameter, Charon is about half the size of Pluto, and was only discovered in 1978.  Quite how it formed has been the subject of much debate. Prior to New Horizons’ visit, the most popular theory was that Charon coalesced from the debris of a collision between Pluto and another Kuiper belt object. However, New Horizons has so far failed to return any images of Pluto that hint at such a collision, and the make-up of the two worlds is less similar than might be expected were one the offshoot of the other. So the theory gaining ground now is that both bodies were already formed when they fell into orbit around one another.

A comparison of the Moons of Pluto as images by New Horizons, and their relative size
A comparison of the Moons of Pluto as images by New Horizons, and their relative size

The latest images of Charon reveal a striking world, every bit as varied as Pluto, and marked by a massive series of fractures across its midriff, suggesting a massive upheaval in Charon’s past which split open its crust. The southern hemisphere also has a more youthful appearance than the region north of the fracture, suggesting that widespread resurfacing took place following the event, and that cryovolcanism (ice volcanoes) may today be contributing to maintaining the relatively smooth appearance of Charon’s southern regions. So like Pluto, Charon may still be an active world.

Continue reading “Space Sunday: from the Sun to Charon, and the death of a planet” →

Space Sunday: of blood moons, Mars, Pluto and Ceres

Posted on by Inara Pey
A lunar eclipse "blood moon" seen Idaho, December 2011 (image: Matt Mills / Reuters)
A lunar eclipse “blood moon” seen Idaho, December 2011 (image: Matt Mills / Reuters)

The night of Sunday 27th / Monday 28th September  promises a very special astronomical event for those fortunate enough to have clear skies overhead and are willing to stay up late (in the UK and Europe). It will see a total lunar eclipse take place at the time when the Moon reaches perigee, its closest approach to Earth in its orbit and giving rise to both a so-called “supermoon” and a “Blood Moon”.

A “supermoon” occurs when a full moon coincides with the time when the Moon is nearing its minimum distance to Earth, a distance of roughly 363,000 kilometres (226,875 miles), leading to it appearing 7-8% larger than when seen as a full Moon at other points in its orbit. A “blood moon” is the result of the Earth’s atmosphere, lying between the Sun and Moon, scatter blue light more strongly than red, so the latter reaches the Moon more strongly, giving it a reddish-brown colour when seen from Earth.

A total lunar eclipse occurs when the Sun, Earth and Moon are lined up so that th Earth is between the Sun and Moon, and the later sits within the Earth's shadow
A total lunar eclipse occurs when the Sun, Earth and Moon are lined up so that the Earth is between the Sun and Moon, and the latter sits within the Earth’s shadow (image: NASA)

Lunar eclipses are not that rare – this one will be the second of 2015, for example. However, “supermoons” are somewhat rarer. The last was in 1982, and the next will not be until 2033. So, if you want to see a really big blood moon, and you live in Western Europe, West Africa, the Eastern side of the USA and Canada or south America, then the 27th / 28th September is the night to do so. People further afield – eastern Asia, the middle east, eastern Europe and the western sides of Canada, the USA and South America will see a partial eclipse.

In the UK, the period of eclipse will start at around 01:00 BST (00:00 GMT) on the morning of Monday, 28th September, and run through until around 05:00 BST (04:00 GMT). That’s from 20:00 through to around 01:00 EDT in the USA / Canada, and 02:00 through 06:00 CET in Europe).

A total lunar eclipse and the gradual change in the Moon’s colour as seen from Earth which sees total lunar eclipses sometimes referred to as “blood moons” – the result of sunlight passing through the Earth’s atmosphere and striking the Moon’s surface (animation: Wikipedia)

The eclipse brings to a close what is referred to as a “tetrad” of total lunar eclipses – that is, four occurring “back-to-back”, with no partial eclipses between them, the first of which occurred in April 2014 and the “middle two” in October 2014 and April 2015. Some have a misguided view that this “tetrad” as being of particular significance because such events are “rare”, and this particular one started on the Passover.

However, while there can be long periods of time between occurrences of tetrads, they can also pop-up relatively frequently. For example, this century will see a total of nine tetrads occur, the first having taken place in 2003/4. Nor is the fact that this particular series started on the Passover particularly unusual; there have been eight tetrads so far coinciding with Passover since the first century AD.

So, if you are in a position to see the eclipse, you can leave the tinfoil hat on the table and step outside quite safely. Totality should occur around two hours after the eclipse starts (e.g. 03:00 BST in the UK / 04:00 CET, 22:00 EDT on the 27th September), and that’s the best time to enjoy the blood moon in all its glory.

The eclipse will also give NASA the chance to measure the full range of temperature variations during  such an event. This will be done by the Lunar Reconnaissance Orbiter (LRO), a solar-power vehicle which has been observing the Moon since 2009.

Normally during an eclipse, the LRO has most of its systems powered down to reduce the load placed on the battery systems. However, mission controllers are confident they will be able to run an instrument which will allow it to accurately measure the amount of heat loss the surface of the Moon experiences when inside the Earth’s shadow, further helping them to understand the composition of the Moon’s regolith and its function as an insulator.

Continue reading “Space Sunday: of blood moons, Mars, Pluto and Ceres” →

Space Sunday: see Pluto’s mountains and the size of the Solar System

Posted on by Inara Pey
Back lit by the sun: Pluto's hazy atmosphere seen from just 18,000km (11,000 miles) and 15 minutes are the point of closest approach to the planet by the New Horizons spacecraft on July 14th, 2015. To the upper right of the planet can be seen the icy expanse of "Sputnik Planum", bordered below and to the left by tall mountains, and to the right by what appears to be glacial outflows. Image courtesy of NASA / JHU / APL,
Backlit by the Sun: Pluto’s hazy atmosphere seen from just 18,000km (11,000 miles) and 15 minutes are the point of closest approach to the planet by the New Horizons spacecraft on July 14th, 2015. To the upper right of the planet can be seen the icy expanse of “Sputnik Planum”, bordered below and to the left by tall mountains, and to the right by what appears to be glacial inflows. Image: NASA / JHUAPL / SwRI (click for full size)

Just when you thought images of Pluto returned by the New Horizons spacecraft could get any more awe-inspiring, NASA / JHU  APL release a set of raw images that are utterly stunning.

The images come from the wide-angle Ralph/Multispectral Visual Imaging Camera (MVIC) on the space craft and were captured just 15 minutes after the vehicle reached is point of closest approach to the little world, and thus from a distance of just 18,000 km (11,000 miles) from Pluto.

The stunning vistas presented in the image show the ice plains of “Sputnik Planum” bordered to the left and from below by Pluto’s huge mountain ranges, informally named Hillary and Norgay, Montes after the first partnership to successful reach the summit of Mt. Everest here on Earth. All of this is dramatically backlit by sunlight reflected through Pluto’s hazy atmosphere to create a wonderful scene said to be reminiscent of views of the Antarctic viewed from space or very high altitude.

A closer view: In this image just 380 km (230 miles) across, shows "Sputnik Planum" bordered to the west by towering mountains reaching up to 3,500 metres (11,000 ft) in altitude. In the foreground sit the informally-named Norgay Montes, and on the skyline to the top and left of the image, the Hilary Montes
A closer view: in this image just 380 km (230 miles) across, shows “Sputnik Planum” bordered to the west by towering mountains reaching up to 3,500 metres (11,000 ft) in altitude. In the foreground sit the informally named Norgay Montes, and on the skyline to the top and left of the image, the Hillary Montes. Image: NASA / JHUAPL / SwRI (click for full size)

However, the images aren’t just notable for the panoramic beauty; they actually reveal a lot about what is happening in the Plutoian atmosphere. Because of the back lighting from the Sun, the high-resolution MVIC has revealed just how complex Pluto’s atmosphere is, comprising multiple layers of nitrogen and other gases rising to around 100 km (60 mi) above Pluto’s surface (and visible as a banding in the images above).

“In addition to being visually stunning, these low-lying hazes hint at the weather changing from day-to-day on Pluto, just like it does here on Earth,” said Will Grundy, lead of the New Horizons Composition team from Lowell Observatory, Flagstaff, Arizona.

What is also exciting the science team is evidence within the images for Pluto having a complex “hydrological” cycle which seems to be comparable in some ways to that found on Earth – only on Pluto, it involves nitrogen ice, rather than water ice.

When compared with images captured as New Horizons approached Pluto, the MVIC images further suggest that the regions eastward of “Sputnik Planum” appear to have been encroached over time by ices and material possibly evaporated from the surface of “Sputnik Planum” to be deposited on the higher lands as a new ice blanket, which in turn appears to have formed glacial formations flowing back into “Sputnik Planum”.

Glacial flow on Pluto: deposits of frozen nitrogen which have accumulated on the uplands on the right side of this 630 km (390 mi) wide image has formed glacial flows leading from the uplands beck into "Sputnik Planum" draining from Pluto’s mountains onto the icy plain through the valley system indicated by the red arrows (the valleys average between 3 and 8 km (2 and 5 mi) in width). In the meantime, the ice of the plain appears to be flowing outwards and towards the uplands, as indicated by the blue arrows. Image: NASA/JHUAPL/SwRI.
Glacial flow on Pluto: deposits of frozen nitrogen which have accumulated on the uplands on the right side of this 630 km (390 mi) wide image has formed glacial flows leading from the uplands beck into “Sputnik Planum” draining from Pluto’s mountains onto the icy plain through the valley system indicated by the red arrows (the valleys average between 3 and 8 km (2 and 5 mi) in width). In the meantime, the ice of the plain appears to be flowing outwards and towards the uplands, as indicated by the blue arrows. Image: NASA / JHUAPL / SwRI (click for full size)

“We did not expect to find hints of a nitrogen-based glacial cycle on Pluto operating in the frigid conditions of the outer solar system,” said Alan Howard, a member of the mission’s Geology, Geophysics and Imaging team from the University of Virginia, Charlottesville. “Driven by dim sunlight, this would be directly comparable to the hydrological cycle that feeds ice caps on Earth, where water is evaporated from the oceans, falls as snow, and returns to the seas through glacial flow.”

To Scale: The Solar System

We’re all familiar with the idea that the solar system is so vast, that it is almost impossible to show the Sun and the major planets proportional to one another and at a scale where all the later are both visible and have orbits which can be adequately encompassed in an easily viewable space.

1972: The Blue Marble (click to enlarge)

Obviously, some models do exist; the Lowell Observatory in Arizona, USA, for example, has a walk that allows visitors to travel from the sun and by each of the planets, but it’s not always easy to clearly grasp the sheer scale of things. The same goes for digital models (and a few have been built within virtual worlds like Second Life).

With this issue of scale and proportion in mind, Wylie Overstreet and Alex Gorosh set out to produce a scale model of the solar system that might help people understand just how vast our planetary back yard is when looked at on a human scale.

They started with a blue marble to represent the Earth, echoing the famous photograph taken on December 7, 1972, by the crew of Apollo 17 en route to the Moon and which NASA dubbed the Blue Marble.

Continue reading “Space Sunday: see Pluto’s mountains and the size of the Solar System” →

Space Sunday: images of meteors, aurorae and comets

Posted on by Inara Pey
A composite image of the Perseids by Jeff Sullivan
A composite image of the Perseids by Jeff Sullivan showing roughly half of the meteors he captured on film in a 3-hour period over the Mojave Desert, California, on August 13th

Visually, it’s been a stunning week for astronomy and space science. We’ve had amazing images of the Perseids reaching this year’s peak as the Earth ploughs through the heart of the debris cloud left by comet Swift-Tuttle; there have been amazing shots of the Northern Lights Tweeted to Earth from the International Space Station; and another comet – 67P/Churyumov–Gerasimenko has shown us just how active a place it came become under the influence of the sun.

As I noted last Sunday, the Perseids meteor shower promised to be quite a spectacle this year, once again coinciding with a new moon which would leave the night skies particularly dark – ideal circumstances with which to see the meteor display for those able to get away from more Earthbound light pollution.

Gary Pearson caught this incredible meteor trail over Brancaster, Norfolk, UK on August 12th - a stunning display from an already vaporised particle of dust
Gary Pearson caught this incredible meteor trail over Brancaster, Norfolk, UK on August 12th – a stunning display from an already vaporised particle of dust

The Perseids – so-called because they appear to originate from the constellation of Perseus – are always a popular astronomical event; during the peak period, it is possible to see between 60 and 100 meteors per hour. They are the result of the Earth travelling through a cloud of dust and debris particles left by  Comet 109p/Swift-Tuttle’s routine passage around the Sun once every 133 years.

As the comet last passed through the inner solar system in 1992, the debris left by the outgassing of material as it was heated by the Sun is extensive, hence the brilliance of the Perseids displays. As noted, with the peak of the Earth’s passage through the debris (which lasts about a month overall from mid-July through mid-August, so there is still time to see them) occurring at a time when there would be a new moon, 2015 promised to offer spectacular opportunities for seeing meteors – and duly delivered.

Amateur astronomers Stojan Stojanovski, Kristijan Gjoreski and Igor Nastoski of the Ohrid Astronomy Association in Ohrid, Macedonia
Amateur astronomers Stojan Stojanovski, Kristijan Gjoreski and Igor Nastoski of the Ohrid Astronomy Association in Ohrid, Macedonia, captured this meteor as the Sun set on August 13th

Across the northern hemisphere between August 12th and August 14th, 2015, the Perseids put on some of the most spectacular displays seen in our skies in recent years – and people were out with their cameras to capture the event.

The highest concentration of meteors was visible after 03:00 local time around the world, although by far the best position to witness the event was in the northern hemisphere, with things getting under way as the skies darkened from about 23:00 onwards in most places.

It is not uncommon for the shower to coincide with a new moon (2012, for example was the same). However, this year’s display has been particularly impressive for those fortunate enough to have clear skies overhead.  “I have been outside for about 3 hours” Ruslan Merzlyako reported on August 13th. “And the results are bloody fantastic! Lots of Perseids and Northern Lights had just exploded in the sky right over my home town. For now, I am not going to argue with Danish weather, because I am 200 percent happy!”

A composite image by Danish photographer Ruslan Merzlyakov, who also caught the background glow of the Northern Lights in the skies of Denmark
A composite image by Danish photographer Ruslan Merzlyakov, who also caught the background glow of the Northern Lights in the skies of Denmark

You can find more images of this year’s Perseids event on Flickr.

Aurora From Space

Staying with the Northern Lights – more formally referred to as the Aurora Borealis –  the current commander of the International Space Station, Scott Kelly, captured some stunning images of the event, some of which he shared via his Twitter feed,  during the 141st day of his current mission – the joint US / Russian Year In Space – aboard the station.

“Aurora trailing a colourful veil over Earth this morning. Good morning from @spacestation!” he tweeted at the start of the series, which included a remarkable time-lapse video. With a further image, he commented, “Another pass through #Aurora. The sun is very active today, apparently.”

Continue reading “Space Sunday: images of meteors, aurorae and comets” →

Space Sunday: active Ceres, open Mars, and shooting stars

Posted on by Inara Pey

Dawn mission patch (NASA / JPL)Dawn, the NASA / ESA joint mission to explore two of the solar system’s three “protoplanets” located in the asteroid belt between the orbits of Mars and Jupiter, continues to intrigue scientists as it studies Ceres, the second of its primary targets.

As I reported in June 2015, Dawn is part of a broader effort to better understand the origins of the solar system and how the planets actually formed; all of which might give us greater understanding of how life arose here on Earth.

Launched in September 2007, Dawn arrived at Ceres in March 2015, after a 2.5 year transit flight from Vesta, its first destination, which it had been studying for 14 months following its arrival in July 2011. Because of their relative size – Ceres accounts for around one-third of the total mass of the asteroid belt – both of these airless, rocky bodies are regarded as dwarf planets, rather than “simple” asteroids. However, Ceres is proving to be quite the conundrum.

At the start of July, Dawn completed the first part of its high-altitude survey of Ceres and fired its low-thrust ion drive to start a series of gentle manoeuvres to reduce its orbit around from 4,400 kilometres (2,700 miles) to 1,450 kilometres (900 miles). It’s now hoped that from this lower orbit, the space craft will be able to discover more about some of Ceres’ more mysterious features.

One in particular has been the subject of much debate. It started when Dawn imaged a series of bright spots within the crater Occator as it made its initial loop around Ceres to enter orbit. Since that time, it has repeatedly images the bright spots, and their presence has also been confirmed by the Hubble Space Telescope.

A June 6th image of the bright spots within a crater on Ceres, captured by Dawn on June 6th, 2015, from a distance of
A Dawn spacecraft image of the bright spots within a crater on Ceres, captured on June 6th, 2015. With the vehicle now entering a much lower altitude mapping mission, it is hoped that even more detail on the spots  – and the faint haze discovered within the crater – will be obtained

Currently, it is believed the bright marks might either be salt deposits or water ice (the European  Herschel Space Observatory had previously found evidence of water vapour on Ceres).  However, while the science team aren’t leaning either way, their mission briefing on July 21st, leant some weight to the bright spots perhaps being water ice. This came in the form of an announcement that he 92 kilometre (57 mile) wide Occator has its own, very localised atmosphere focused around the bright areas.

The evidence for this comes from images of the crater taken from certain angles which reveal a thin haze covering around half of the cater, but not extending beyond its walls. Th thinking is that this haze is perhaps the result of the ice in the bright area – if they are ice – sublimating out.

However, if this is the case, it actually raises a further mystery: why the haze? Generally, such sublimation would lead to the resulting gases dissipating very quickly, without forming a haze. One hypothesis is that Ceres’ gravity, which is somewhat higher than might be expected for a body of its size) may be and influencing factor.

The 5 km high "pyramid" mountain pokes up above the limb of Ceres. Flat-topped, it has streaks of bight mateiral on its flanks giving the impression something has been flowing down it.
The 5 km high “pyramid” mountain pokes up above the limb of Ceres. Flat-topped, it has streaks of bright material on its flanks giving the impression something has been flowing down it.

The bright spots aren’t the only curious feature on Ceres. Dawn has also spotted numerous long, linear features whose cause is unknown, as well as one big mountain that mission team members have dubbed “The Pyramid.” This massif, about 5 km (3 mi) in height, and around 30 km (19 mi) across at its base, is oddly flat-topped and has streaks of bright material on one of it flanks, as if something has been cascading down the slope. What this might indicate has planetary scientists scratching their heads at this point.

With all the mysteries thrown up by New Horizon’s recently flyby of Pluto, and Dawn’s discovery of mysterious features on Ceres, it really is becoming a case that the tiny worlds of our solar system are perhaps the most perplexing.

Three years ago, in August 2012, NASA’s Mars Science Laboratory rover, Curiosity, arrived in Gale Crater, Mars. Since that time, the rover has made some remarkable discoveries, as reported in this blog over the years.

To mark the anniversary of the landing, NASA has launched two new on-line tools designed to open the mysterious terrain of the Red Planet to anyone with an interest in planetary exploration.

Experience Curiosity allows users to journey along with the one-tonne rover on its Martian expeditions. The program simulates Mars in 3-D, using actual data returned by the rover and NASA’s Mars Reconnaissance Orbiter (MRO). It also uses a  game-ready rover model based entirely on real mechanisms.

Experience Curiosity allows you to learn about the rover using a 3D model which can be manipulated and driven, using a WebGL application
Experience Curiosity allows you to learn about the rover using a 3D model which can be manipulated and driven, using a WebGL application

User are able to drive the rover, examine it, call up data on key components, witness the driving view from different cameras on the rover, and operated the robot arm. Activities are a little basic, but as this appears to be a part of NASA’s Eyes On project, capabilities may grow over time.

Mars Trek is a much more expansive tool – one which is actually being used in the planning for the Mars 2020 rover mission. It features interactive maps, which include the ability to overlay a range of data sets generated from instruments aboard spacecraft orbiting Mars, and analysis tools for measuring surface features. Standard keyboard gaming controls are used to manoeuvre the user across Mars’ surface, and topographic data can be exported to 3D printers to allow the printing of physical models of surface features.

The map view and be manipulated in 2D or 3D, data on various surface missions is provided, compete with the ability to zoom into the surface locations for these missions, making for a visually impressive model.

Continue reading “Space Sunday: active Ceres, open Mars, and shooting stars” →