“Bricks have been 3D printed out of simulated moondust using concentrated sunlight. This ESA project took place at the DLR German Aerospace Center facility in Cologne, with a 3D printer table attached to a solar furnace, baking successive 0.1 mm layers of moondust at a temperature of 1000°C. A 20 x 10 x 3 cm brick for building can be completed in around five hours. DLR Cologne’s solar furnace has two working setups: as a baseline, it uses 147 curved mirror facets to focus either actual sunlight into a high temperature beam, employed to melt together the grains of regolith. But this mode is weather dependent, so a solar simulator was subsequently employed as well – based on an array of xenon lamps more typically found in cinema projectors.”
“As seen from the Earth, a solar eclipse is a type of eclipse that occurs when the Moon passes between the Sun and Earth, and the Moon fully or partially blocks (“occults”) the Sun. This can happen only at new moon when the Sun and the Moon are in conjunction as seen from Earth in an alignment referred to as syzygy. In a total eclipse, the disk of the Sun is fully obscured by the Moon. In partial and annular eclipses, only part of the Sun is obscured.
If the Moon were in a perfectly circular orbit, a little closer to the Earth, and in the same orbital plane, there would be total solar eclipses every month. However, the Moon’s orbit is inclined (tilted) at more than 5 degrees to the Earth’s orbit around the Sun (see ecliptic), so its shadow at new moon usually misses Earth. Earth’s orbit is called the ecliptic plane as the Moon’s orbit must cross this plane in order for an eclipse (both solar as well as lunar) to occur. In addition, the Moon’s actual orbit is elliptical, often taking it far enough away from Earth that its apparent size is not large enough to block the Sun totally. The orbital planes cross each other at a line of nodes resulting in at least two, and up to five, solar eclipses occurring each year; no more than two of which can be total eclipses. However, total solar eclipses are rare at any particular location because totality exists only along a narrow path on the Earth’s surface traced by the Moon’s shadow or umbra.
An eclipse is a natural phenomenon. Nevertheless, in some ancient and modern cultures, solar eclipses have been attributed to supernatural causes or regarded as bad omens. A total solar eclipse can be frightening to people who are unaware of its astronomical explanation, as the Sun seems to disappear during the day and the sky darkens in a matter of minutes.
Since looking directly at the Sun can lead to permanent eye damage or blindness, special eye protection or indirect viewing techniques are used when viewing a solar eclipse. It is technically safe to view only the total phase of a total solar eclipse with the unaided eye and without protection; however, this is a dangerous practice, as most people are not trained to recognize the phases of an eclipse, which can span over two hours while the total phase can only last a maximum of 7.5 minutes for any one location. People referred to as eclipse chasers or umbraphiles will travel to remote locations to observe or witness predicted central solar eclipses.”
“Video, based on measurements by ESA’s Gaia and Hipparcos satellites, shows how our view of the Orion constellation will evolve over the next 450 000 years. Stars are not motionless in the sky: their positions change continuously as they move through our Galaxy, the Milky Way. These motions, too slow to be appreciated with the naked eye over a human lifetime, can be captured by high-precision observations like those performed by ESA’s billion-star surveyor, Gaia. By measuring their current movements, we can reconstruct the past trajectories of stars through the Milky Way to study the origins of our Galaxy, and even estimate stellar paths millions of years into the future. This video provides us with a glimpse over the coming 450 000 years, showing the expected evolution of a familiar patch of the sky, featuring the constellation of Orion, the Hunter.
The portion of the sky depicted in the video measures 40 x 20º – as a comparison, the diameter of the full Moon in the sky is about half a degree. Amid a myriad of drifting stars, the shape of Orion as defined by its brightest stars is slowly rearranged into a new pattern as time goes by, revealing how constellations are ephemeral. The red supergiant star Betelgeuse is visible at the centre towards the top of the frame at the beginning of the video (represented in a yellow–orange hue). According to its current motion, the star will move out of this field of view in about 100 000 years. The Universe has a much harsher fate in store for Betelgeuse, which is expected to explode as a supernova within the next million of years.
More of the stars shown in this view will have exploded as supernovas before the end of the video, while others might be still evolving towards that end, like Orion’s blue supergiant, Rigel, visible as the bright star in the lower left, or the red giant Aldebaran, which is part of the constellation Taurus, and can be seen crossing the lower part of the frame from right to left. Many new stars will also have been born from the Orion molecular cloud, a mixture of gas and dust that is not directly seen by Gaia – it can be identified as dark patches against the backdrop of stars – but shines brightly at infrared wavelengths. The birth and demise of stars are not shown in the video. The Hyades cluster, a group of stars that are physically bound together and are also part of the Taurus constellation, slowly makes its way from the lower right corner to the upper left.
The new video is based on data from the Tycho–Gaia Astrometric Solution, a resource that lists distances and motions for two million stars in common between Gaia’s first data release and the Tycho-2 Catalogue from the Hipparcos mission. Additional information from ground-based observations were included, as well as data from the Hipparcos catalogue for the brightest stars in the view.”
“The Larsen Ice Shelf is a long, fringing ice shelf in the northwest part of the Weddell Sea, extending along the east coast of the Antarctic Peninsula from Cape Longing to the area just southward of Hearst Island. It is named for Captain Carl Anton Larsen, the master of the Norwegian whaling vessel Jason, who sailed along the ice front as far as 68°10′ South during December 1893. In finer detail, the Larsen Ice Shelf is a series of shelves that occupy (or occupied) distinct embayments along the coast. From north to south, the segments are called Larsen A (the smallest), Larsen B, and Larsen C (the largest) by researchers who work in the area. Further south, Larsen D and the much smaller Larsen E, F and G are also named. The breakup of the ice shelf since the mid 1990s has been widely reported, with the collapse of Larsen B in 2002 being particularly dramatic.
Larsen C is the fourth largest ice shelf in Antarctica, with an area of about 50,000 km2 (19,000 sq mi). In 2004, a report concluded that although the remaining Larsen C region appeared to be relatively stable, continued warming could lead to its breakup within the next decade. News reports in summer of 2016 suggested that this process has begun. On 10 November 2016 scientists photographed the growing rift running along the Larsen C ice shelf, showing it running about 110 kilometres (68 mi) long with a width of more than 91 m (299 ft), and a depth of 500 m (1,600 ft). By December 2016, the rift had extended another 21 km (13 mi) to the point where only 20 km (12 mi) of unbroken ice remained and calving was considered to be a certainty in 2017. This will cause the collapse of between nine and twelve percent of the ice shelf, 6,000 km2 (2,300 sq mi), an area greater than the size of the US state of Delaware. After calving, the broken fragment will be 350 m (1,150 ft) thick and have an area of about 5,000 km2 (1,900 sq mi). If it calves without breaking into small fragments, it will be among the largest icebergs ever recorded.
On 1 May 2017 members of the Antarctic research group Project MIDAS, a British Antarctic research project observing the ever-growing crack, reported that satellite images showed a new crack, around 9 miles long (15 kilometers), branching off the main crack approximately six miles behind the previous tip, heading toward the ice front. Scientists with Swansea University in the UK say the crack lengthened 11 miles from 25 May to 31 May, and that less than 8 miles of ice is all that prevents the birth of an enormous iceberg.
Since the ice shelf is already floating, its departure from Antartica would not affect global sea levels. But a number of glaciers discharge onto it from the lands behind the ice shelf, and therefore might flow faster if it breaks away from the continent. If all the ice that the Larsen C shelf currently holds back were to enter the sea, it is estimated that global waters would rise by 10 cm (4 in).”
“Reiner Gamma (γ) is a geographical feature of the Moon known as a lunar swirl. It is one of the most visible lunar swirls from Earth, visible from most telescopes. It was originally thought to be a lunar highland, but scientists eventually realized that it cast no shadow on the moon. Until recently, Reiner Gamma’s origin was a mystery. Historically, it was not associated with any particular irregularities in the surface. Recently, similar features were discovered in Mare Ingenii and Mare Marginis by orbiting spacecraft. The feature on Mare Ingenii is located at the lunar opposite point from the center of Mare Imbrium. Likewise the feature on Mare Marginis is opposite the midpoint of Mare Orientale. Thus scientists believe that the feature resulted from seismic energies generated by the impacts that created these maria. Unfortunately there is no such lunar mare formation on the opposite surface of the Moon (although the large crater Tsiolkovskiy lies within one crater diameter).
Reiner Gamma is located on the Oceanus Procellarum, west of the crater Reiner. Its center is located at selenographic coordinates 7.5°N 59.0°W. It has an overall dimension of about 70 kilometres. The feature has a higher albedo than the relatively dark mare surface, with a diffuse appearance and a distinctive swirling, concentric oval shape. Related albedo features continue across the surface to the east and southwest, forming loop-like patterns over the mare. The central feature of Reiner Gamma resembles the dipolar formation created by iron filings on a surface with a bar magnet on the underside. Low-orbiting spacecraft have observed a relatively strong magnetic field associated with each of these albedo markings. Some have speculated that this magnetic field and the patterns were created by cometary impacts. However the true cause remains uncertain.
Reiner Gamma’s magnetic field strength is approximately 15 nT, measured from an altitude of 28 km. This is one of the strongest localized magnetic anomalies on the Moon. The surface field strength of this feature is sufficient to form a mini-magnetosphere that spans 360 km at the surface, forming a 300 km thick region of enhanced plasma where the solar wind flows around the field. As the particles in the solar wind are known to darken the lunar surface, the magnetic field at this site may account for the survival of this albedo feature.
In early lunar maps by Francesco Maria Grimaldi, this feature was incorrectly identified as a crater. His colleague Giovanni Riccioli then named it Galilaeus, after Galileo Galilei. The name was later transferred northwest to the current crater Galilaei.”
“ESA’s Swarm satellites are seeing fine details in one of the most difficult layers of Earth’s magnetic field to unpick – as well as our planet’s magnetic history imprinted on Earth’s crust. Earth’s magnetic field can be thought of as a huge cocoon, protecting us from cosmic radiation and charged particles that bombard our planet in solar wind. Without it, life as we know it would not exist. Most of the field is generated at depths greater than 3000 km by the movement of molten iron in the outer core. The remaining 6% is partly due to electrical currents in space surrounding Earth, and partly due to magnetised rocks in the upper lithosphere – the rigid outer part of Earth, consisting of the crust and upper mantle.
Although this ‘lithospheric magnetic field’ is very weak and therefore difficult to detect from space, the Swarm trio is able to map its magnetic signals. After three years of collecting data, the highest resolution map of this field from space to date has been released.
“By combining Swarm measurements with historical data from the German CHAMP satellite, and using a new modelling technique, it was possible to extract the tiny magnetic signals of crustal magnetisation,†explained Nils Olsen from the Technical University of Denmark, one of the scientists behind the new map. ESA’s Swarm mission manager, Rune Floberghagen, added: “Understanding the crust of our home planet is no easy feat. We can’t simply drill through it to measure its structure, composition and history. “Measurements from space have great value as they offer a sharp global view on the magnetic structure of our planet’s rigid outer shell.â€
The magnetic field is in a permanent state of flux. Magnetic north wanders, and every few hundred thousand years the polarity flips so that a compass would point south instead of north. When new crust is generated through volcanic activity, mainly along the ocean floor, iron-rich minerals in the solidifying magma are oriented towards magnetic north, thus capturing a ‘snapshot’ of the magnetic field in the state it was in when the rocks cooled. Since magnetic poles flip back and forth over time, the solidified minerals form ‘stripes’ on the seafloor and provide a record of Earth’s magnetic history.”
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