All posts by Tom

Noctilucent Clouds from the ISS

noctilucentcloud

Noctilucent clouds are beautiful and strange at the same time. You can indeed see them from the ground and are a welcome site.

This image was taken on 29 May 2016 by Tim Peake aboard the ISS:

The NASA Image of the Day caption:

Expedition 47 Flight Engineer Tim Peake of the European Space Agency photographed rare, high-altitude noctilucent or “night shining” clouds from the International Space Station on May 29, 2016.

Polar mesospheric clouds — also known as noctilucent clouds – form between 76 to 85 kilometers (47 to 53 miles) above the Earth’s surface, near the boundary of the mesosphere and thermosphere, a region known as the mesopause. At these altitudes, water vapor can freeze into clouds of ice crystals. When the sun is below the horizon and the ground is in darkness, these high clouds may still be illuminated, lending them their ethereal, “night shining” qualities.

In the late spring and summer, unusual clouds form high in the atmosphere above the polar regions of the world. As the lower atmosphere warms, the upper atmosphere gets cooler, and ice crystals form on meteor dust and other particles high in the sky. The result is noctilucent or “night-shining” clouds — electric blue wisps that grow on the edge of space. Polar mesospheric clouds can be observed from both the Earth’s surface and in orbit by astronauts aboard the International Space Station.

Image Credit: ESA/NASA

Active Pluto

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Hard to imagine that a (dwarf) planet so far from the Sun would be as active as Pluto is!

The New Horizon’s caption:
Like a cosmic lava lamp, a large section of Pluto’s icy surface is being constantly renewed by a process called convection that replaces older surface ices with fresher material.

Scientists from NASA’s New Horizons mission used state-of-the-art computer simulations to show that the surface of Pluto’s informally named Sputnik Planum is covered with churning ice “cells” that are geologically young and turning over due to a process called convection. The scene above, which is about 250 miles (400 kilometers) across, uses data from the New Horizons Ralph/Multispectral Visible Imaging Camera (MVIC), gathered July 14, 2015. Their findings are published in the June 2, 2016, issue of the journal Nature.

Image: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

The Juno Team

junoteam

With a month to go before the Juno spacecraft reaches Jupiter and conducts a great mission now is a good time to meet the people flying the spacecraft.

From left to right:
Kenny Starnes – MSA Manager,
Kirsten Francis – Guidance, Navigation and Control Engineer,
Alexandra Hilbert – Systems and Guidance, Navigation and Control Engineer,
Bryce Strauss – Mission Operations Systems Engineer, and
Wil Santiago – Mission Operations Thermal Engineer.

Read about what they do from Lockheed Martin (it’s quick).

Juno art courtesy of NASA/JPL-Caltech

The Transit of the ISS

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This is a remarkable image! I have tried on numerous occasions to get an image of the International Space Station as it passes over the disk of the Sun, something always goes wrong. It is a VERY difficult endeavor with so many variables.

Then there is a master at the craft of astrophotography:  Thierry Legault. Not only did he capture the ISS, he did it during the transit of Mercury!

This from ESA (be sure to watch the video linked below):

On 9 May Mercury passed in front of the Sun as seen from Earth. These transits of Mercury occur only around 13 times every century, so astronomers all over Earth were eager to capture the event.

For astrophotographer Thierry Legault, capturing Mercury and the Sun alone was not enough, however – he wanted the International Space Station in the frame as well.

To catch the Station passing across the Sun, you need to set up your equipment within a ground track less than 3 km wide. For Thierry, this meant flying to the USA from his home near Paris, France.

On 9 May there were three possible areas to capture the Station and Mercury at the same time against the solar disc: Quebec, Canada, the Great Lakes and Florida, USA.

Choosing the right spot took considerable effort, says Thierry: “Canada had bad weather predicted and around Florida I couldn’t find a suitably quiet but public place, so I went to the suburbs of Philadelphia.”

With 45 kg of equipment, Thierry flew to New York and drove two hours to Philadelphia to scout the best spot. Even then, all the preparations and intercontinental travel could have been for nothing because the Station crosses the Sun in less than a second and any clouds could have ruined the shot.

“I was very lucky: 10 minutes after I took the photos, clouds covered the sky,” says a relieved Thierry.

“Adrenaline flows in the moments before the Station flies by – it is a one-shot chance. I cannot ask the space agencies to turn around so I can try again. Anything can happen.”

The hard work and luck paid off. The image here includes frames superimposed on each other to show the Station’s path. Mercury appears as a black dot at bottom-centre of the Sun.

For Thierry, the preparation and the hunt for the perfect shot is the best part.

“Astrophotography is my hobby that I spend many hours on, but even without a camera I encourage everybody to look up at the night sky. The International Space Station can be seen quite often and there are many more things to see. It is just a case of looking up at the right time.”

Watch a video of the pass, including another moment with an aircraft flying by. 

Visit Thierry’s homepage here: http://www.astrophoto.fr/

Image and caption: Thierry Legault and ESA

Making a Brown Dwarf

browndwarfcannible

When I think of a brown dwarf I think of a stellar body that doesn’t have quite enough mass to become a full fledged star.  Now it seems there is an example of a brown dwarf being formed because a companion has taken so much mass from a regular star it has actually been downgraded according to researchers.

From SpaceRef:
Astronomers have detected a sub-stellar object that used to be a star, after being consumed by its white dwarf companion.

An international team of astronomers made the discovery by observing a very faint binary system, J1433 which is located 730 light-years away. The system consists of a low-mass object – about 60 times the mass of Jupiter – in an extremely tight 78-minute orbit around a white dwarf (the remnant of a star like our Sun).

Due to their close proximity, the white dwarf strips mass from its low-mass companion. This process has removed about 90 per cent of the mass of the companion, turning it from a star into a brown dwarf.

Most brown dwarfs are ‘failed stars’, objects that were born with too little mass to shine brightly by fusing hydrogen in their cores. By contrast, the brown dwarf in this system was born as a full-fledged star, but has been stripped to its current mass by billions of years of stellar cannibalism.
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Janus and Mimas

mimasandjanus

About the image:
Saturn’s moons Janus and Mimas coast in their silent orbits beyond the rings in this view from NASA’s Cassini spacecraft. The ansa, or outer edge of the rings, is visible at left. Janus hangs above center, while Mimas shines at right. Owing to its irregular shape, Janus’ terminator — that line which separates day from night — is jagged, while Mimas’ smooth terminator belies its round shape and larger size.

The image was taken in green light with Cassini’s narrow-angle camera on Oct. 27, 2015.

The view was acquired at a distance of approximately 598,000 miles (963,000 kilometers) from Janus and at a Sun-Janus-spacecraft, or phase, angle of 86 degrees. Image scale at Janus is 3.6 miles (5.8 kilometers) per pixel. The distance to Mimas was 680,000 miles (1.1 million kilometers) for an image scale of 4.1 miles (6.6 kilometer) per pixel.

Image and caption: NASA/JPL-Caltech/Space Science Institute

Herschel’s Little Fox

herschelfox
Herschel and ESA (via NASA):

New stars are the lifeblood of our galaxy, and there is enough material revealed by this Herschel infrared image to build stars for millions of years to come.

Situated 8,000 light-years away in the constellation Vulpecula — Latin for “little fox” — the region in the image is known as Vulpecula OB1. It is a “stellar association” in which a batch of truly giant “OB” stars is being born. O and B stars are the largest stars that can form.

The giant stars at the heart of Vulpecula OB1 are some of the biggest in the galaxy. Containing dozens of times the mass of the sun, they have short lives, astronomically speaking, because they burn their fuel so quickly. At an estimated age of 2 million years, they are already well through their lifespans. When their fuel runs out, they will collapse and explode as supernovas. The shock this will send through the surrounding cloud will trigger the birth of even more stars, and the cycle will begin again.

O stars are at least 16 times more massive than the sun, and could be well over 100 times as massive. They are anywhere from 30,000 to 1 million times brighter than the sun, but they only live up to a few million years before exploding. B-stars are between two and 16 times as massive as the sun. They can range from 25 to 30,000 times brighter than the sun.

OB associations are regions with collections of O and B stars. Since OB stars have such short lives, finding them in large numbers indicates the region must be a strong site of ongoing star formation, which will include many more smaller stars that will survive far longer.

The vast quantities of ultraviolet light and other radiation emitted by these stars is compressing the surrounding cloud, causing nearby regions of dust and gas to begin the collapse into more new stars. In time, this process will “eat” its way through the cloud, transforming some of the raw material into shining new stars.

The image was obtained as part of Herschel’s Hi-GAL key-project. This used the infrared space observatory’s instruments to image the entire galactic plane in five different infrared wavelengths.

These wavelengths reveal cold material, most of it between -220º C and -260º C. None of it can be seen in ordinary optical wavelengths, but this infrared view shows astronomers a surprising amount of structure in the cloud’s interior.

The surprise is that the Hi-GAL survey has revealed a spider’s web of filaments that stretches across the star-forming regions of our galaxy. Part of this vast network can be seen in this image as a filigree of red and orange threads.

In visual wavelengths, the OB association is linked to a star cluster catalogued as NGC 6823. It was discovered by William Herschel in 1785 and contains 50 to 100 stars. A nebula emitting visible light, catalogued as NGC 6820, is also part of this multi-faceted star-forming region.

Herschel is a European Space Agency mission, with science instruments provided by consortia of European institutes and with important participation by NASA. While the observatory stopped making science observations in April 2013, after running out of liquid coolant as expected, scientists continue to analyze its data. NASA’s Herschel Project Office is based at NASA’s Jet Propulsion Laboratory, Pasadena, California. JPL contributed mission-enabling technology for two of Herschel’s three science instruments. The NASA Herschel Science Center, part of the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, supports the U.S. astronomical community. Caltech manages JPL for NASA.

Image: ESA/Herschel/PACS, SPIRE/Hi-GAL Project