Solar eclipse, 21 August 2017

This video from the USA says about itself:

Eclipses Throughout our Universe | Out There | Solar Eclipse 2017

14 aug. 2017

On the 21st day of August, 2017, the moon will slide between the Earth and the sun, painting a swath of darkness across North America. The Great American Solar Eclipse.

An exercise in cosmic geometry. A reminder that we live on one sphere among many, all moving to the laws of Kepler, Newton and Einstein. The moon’s orbit around the Earth is slightly tilted, so the shadow of the new moon usually passes above or below us. About twice a year, the three bodies briefly align, and the moon’s long shadow cuts across our planet. The day dies and is reborn. The sun is replaced by an inky hole, feathered with the pale corona, a million degrees hotter than the sun itself. Staring up into the cone of blackness you can feel the cosmic gears grinding. Two minutes of beauty and terror.

What happens in Earth’s atmosphere during an eclipse? Using smartphones and radio kits, researchers will track changes in how radio waves travel through the ionosphere. By Lisa Grossman, 7:00am, August 13, 2017.

Can the eclipse tell us if Einstein was right about general relativity? He probably was, but astronomers will put his 1915 theory to the test with DIY experiments. By Lisa Grossman, 7:00am, August 15, 2017.

What can we learn about Mercury’s surface during the eclipse? A telescope aboard a pair of research jets will make a thermal map of the planet during the eclipse. By Lisa Grossman, 7:00am, August 14, 2017.


Planet Mercury transit, 9 May

This video says about itself:

7 April 2016

A transit of Mercury is taking place on 9th May 2016. This is a relatively a rare event: there will be another on 11th November 2019 but, after that, you’ll have to wait until 2032! Learn more here. …

Planets and the Sun on the animation are not to scale.

Mercury’s surface still changing. MESSENGER’s snapshot of cliffs hints at tectonic activity within last 50 million years. By Christopher Crockett, 11:00am, September 26, 2016: here.

Planet Mercury craters named after Diego Rivera, Umm Kulthum, other artists

This video from the USA says about itself:

27 April 2015

The robotic spacecraft MESSENGER has run out of fuel. With no way to make major adjustments to its orbit around the planet Mercury, the probe will smash into the surface at more than 8,750 miles per hour (3.91 kilometers per second). The impact will add a new crater to the planet’s scarred face that engineers estimate will be as wide as 52 feet (16 meters).

From NASA in the USA:

April 29, 2015

Mercury Crater-Naming Contest Winners Announced

The MESSENGER Education and Public Outreach (EPO) Team, coordinated through the Carnegie Institution for Science, announces the winning names from its competition to name five impact craters on Mercury. The contest submissions had to be submitted by January 15, 2015, and the International Astronomical Union (IAU) — the governing body of planetary and satellite nomenclature since 1919 — made the selections from a semi-final submission of 17 artists’ names. The newly selected crater names are Carolan, Enheduanna, Karsh, Kulthum, and Rivera.

Under IAU rules, all new craters on Mercury must be named after an artist, composer, or writer who was famous for more than 50 years and has been dead for more than three years.

Turlough O’Carolan (Carolan), was an Irish composer during the late 1600s and early 1700s.

This music video features Turlough O’Carolan’s composition Planxty Irwin.

Enheduanna, an Akkadian princess who lived in the Sumerian city of Ur in ancient Mesopotamia (today’s Iraq and Kuwait), and is regarded by many scholars as possibly the earliest known author and poet.

This video is about Enheduanna.

Yousuf Karsh, was an Armenian/Canadian and one of the greatest portrait photographers of the twentieth century.

This video is called Profile of Photographer Yousuf Karsh.

Umm Kulthum, was an Egyptian singer, songwriter, and film actress of the 1920s to the 1970s.

This music video is called Umm Kulthum ( أم كلثوم ) live; “Enta Omri” (English subtitles). At the Olympia Théâtre in Paris, November 1967.

Diego Rivera, was a prominent Mexican painter and muralist from the 1920s to the 1950s.

This video is called Tribute to Diego Rivera.

NASA’s MESSENGER spacecraft has been in orbit about Mercury since March 2011 and is due to finally impact the planet tomorrow. The MESSENGER spacecraft has far surpassed expectations in the duration of the mission and in the quantity and quality of data returned. The original goal of the craft was to take 2,500 images of the planet, but is has returned more than 250,000. The EPO team organized the crater-naming competition to celebrate the mission’s achievements.

The winners come from many different countries. Carolan was suggested by Fergal Donnelly (Belgium), Joseph Brusseau (USA), and Reane Morrison (USA). Enheduanna was submitted by Gagan Toor (India). Karsh was submitted by Elizabeth Freeman Rosenzweig (USA). Kulthum was suggested by Malouk Ba-Isa (Saudi Arabia), Riana Rakotoarimanan (Switzerland), Yehya Hassouna (USA), David Suttles (USA), Thorayya Said Giovanelli (USA), and Matt Giovanelli (USA). Rivera was suggested by Ricardo Martinez (Mexico), Rebecca Hare (USA), Arturo Gutierrez (Mexico), and Jose Martinez (USA).

Julie Edmonds, the EPO team leader at the Carnegie Institution for Science, remarked, “The IAU working group that chose the names was very happy with the submissions. In all we had 3,600 contest entries, a resounding success for the excitement that the MESSENGER mission to Mercury has generated.”

Final Maneuver Extends MESSENGER Operations by One More Orbit

MESSENGER mission controllers at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., conducted a maneuver on April 28 designed to raise the spacecraft’s minimum altitude sufficiently to ensure impact onto Mercury during the desired orbit when full coverage by NASA’s Deep Space Network (DSN) scheduled.

The previous maneuver, completed on April 24, raised MESSENGER’s minimum altitude from 8.3 kilometers (5.2 miles) to 18.2 kilometers (11.3 miles) above the planet’s surface. Because of progressive changes to the orbit over time, however, the spacecraft’s minimum altitude continued to decrease.

At the time of this most recent maneuver, MESSENGER was in an orbit with a closest approach of 5.3 kilometers (3.3 miles) above the surface of Mercury. With a velocity change of 0.45 meters per second (1 mile per hour), the spacecraft’s four largest monopropellant thrusters released gaseous helium pressurant to nudge the spacecraft to an orbit with a closest approach altitude of 6.3 kilometers (3.9 miles).

This maneuver also increased the spacecraft’s speed relative to Mercury near the maximum distance from Mercury, adding about 3.5 seconds to the spacecraft’s eight-hour, 21.2-minute orbit period. The final maneuver in the MESSENGER low-altitude hover campaign, this was the mission’s fourth course-correction maneuver to use the helium gas pressurant as a propellant to change the spacecraft’s orbit. This view shows MESSENGER’s orientation at the start of the maneuver.

MESSENGER was 155.2 million kilometers (96.5 million miles) from Earth when the 3.02-minute maneuver began at about 5:20 p.m. EDT. Mission controllers at APL verified the start of the maneuver 8.6 minutes later, after the first signals indicating spacecraft thruster activity reached NASA’s DSN tracking station in Goldstone, California.

MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a NASA-sponsored scientific investigation of the planet Mercury and the first space mission designed to orbit the planet closest to the Sun. The MESSENGER spacecraft was launched on August 3, 2004, and entered orbit about Mercury on March 18, 2011, to begin a yearlong study of its target planet. MESSENGER’s first extended mission began on March 18, 2012, and ended one year later. MESSENGER is now in a second extended mission, which is scheduled to operate through April 2015.

Mercury, hottest planet, ice discovery

This 29 November 2012 video from the USA is called UCLA Professor David Paige – New Evidence for Water Ice on Mercury.

From daily The Independent in Britain:

Water on Mercury photographed by Nasa for the first time in ‘permanently shadowed’ craters

Images confirm that the planet closest to the Sun has ‘recent’ water deposits

James Vincent

Friday 17 October 2014

Nasa has taken the first ever pictures of water ice on Mercury – the permanently-roasting planet closest to the Sun in our Solar System.

It might sound counter-intuitive to find ice on a planet where surface temperatures hit highs of 430 degrees Celsius every day (a Mercury day is equivalent to 58 Earth days) but impact craters on the poles permanently shadowed from the Sun have been found to provide some much needed shade.

Scientists have thought this might be the case since the mid-1990s, when radio telescopes scanning the planet found areas that strongly reflected radar signals (a good sign that ice is present) with this most recent study is the first to provide optical proof.

The scientist examined a number of impact craters situated around Mercury’s north pole (including the largest, Prokofiev, an indentation just under 70 miles wide) and found that the deposits were made surprisingly recently, with the boundaries of the ice defined by sharped edges not yet smoothed out by time.

“The sharp boundaries indicate that the volatile deposits at Mercury’s poles are geologically young,” wrote the study’s authors in the journal Geology, “and either are restored at the surface through an ongoing process or were delivered to the planet recently.”

If the water was ‘delivered recently’ then it could suggest new mechanisms in the distribution of water-ice in the Solar System – research that might have implications for our own Moon, which is also believed to contain water-ice in areas of permanent shadow.

“If you can understand why one body looks one way and another looks different, you gain insight into the process that’s behind it, which in turn is tied to the age and distribution of water ice in the solar system,” study lead author Nancy Chabot said. “This will be a very interesting line of inquiry going forward.”

Planet earth photographed by spacecraft

Planet earth photographed from space. Two Views of Home: These images show views of Earth and the moon from NASA's Cassini (left) and MESSENGER spacecraft (right) from July 19, 2013. (Credit: NASA/JPL-Caltech/Space Science Institute and NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)

From ScienceDaily:

NASA Releases Images of Earth by Two Interplanetary Spacecraft

July 22, 2013 — Color and black-and-white images of Earth taken by two NASA interplanetary spacecraft on July 19 show our planet and its moon as bright beacons from millions of miles away in space.

NASA’s Cassini spacecraft captured the color images of Earth and the moon from its perch in the Saturn system nearly 900 million miles (1.5 billion kilometers) away. MESSENGER, the first probe to orbit Mercury, took a black-and-white image from a distance of 61 million miles (98 million kilometers) as part of a campaign to search for natural satellites of the planet.

In the Cassini images Earth and the moon appear as mere dots — Earth a pale blue and the moon a stark white, visible between Saturn’s rings. It was the first time Cassini’s highest-resolution camera captured Earth and its moon as two distinct objects.

It also marked the first time people on Earth had advance notice their planet’s portrait was being taken from interplanetary distances. NASA invited the public to celebrate by finding Saturn in their part of the sky, waving at the ringed planet and sharing pictures over the Internet. More than 20,000 people around the world participated.

“We can’t see individual continents or people in this portrait of Earth, but this pale blue dot is a succinct summary of who we were on July 19,” said Linda Spilker, Cassini project scientist, at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “Cassini’s picture reminds us how tiny our home planet is in the vastness of space, and also testifies to the ingenuity of the citizens of this tiny planet to send a robotic spacecraft so far away from home to study Saturn and take a look-back photo of Earth.”

Pictures of Earth from the outer solar system are rare because from that distance, Earth appears very close to our sun. A camera’s sensitive detectors can be damaged by looking directly at the sun, just as a human being can damage his or her retina by doing the same. Cassini was able to take this image because the sun had temporarily moved behind Saturn from the spacecraft’s point of view and most of the light was blocked.

A wide-angle image of Earth will become part of a multi-image picture, or mosaic, of Saturn’s rings, which scientists are assembling. This image is not expected to be available for several weeks because of the time-consuming challenges involved in blending images taken in changing geometry and at vastly different light levels, with faint and extraordinarily bright targets side by side.

“It thrills me to no end that people all over the world took a break from their normal activities to go outside and celebrate the interplanetary salute between robot and maker that these images represent,” said Carolyn Porco, Cassini imaging team lead at the Space Science Institute in Boulder, Colo. “The whole event underscores for me our ‘coming of age’ as planetary explorers.”

In the MESSENGER image, Earth and the moon are less than a pixel, but appear very large because they are overexposed. Long exposures are required to capture as much light as possible from potentially dim objects. Consequently, bright objects in the field of view become saturated and appear artificially large.

“That images of our planet have been acquired on a single day from two distant solar system outposts reminds us of this nation’s stunning technical accomplishments in planetary exploration,” said MESSENGER Principal Investigator Sean Solomon of Columbia University’s Lamont-Doherty Earth Observatory in Palisades, N.Y. “And because Mercury and Saturn are such different outcomes of planetary formation and evolution, these two images also highlight what is special about Earth. There’s no place like home.”

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL designed, developed and assembled the Cassini orbiter and its two onboard cameras. The Johns Hopkins University Applied Physics Laboratory in Laurel, Md., designed and built MESSENGER, a spacecraft developed under NASA’s Discovery Program. NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the program for the agency’s Science Mission Directorate in Washington. JPL and APL manage their respective missions for NASA. The California Institute of Technology in Pasadena manages JPL for NASA.

More information about the picture and the Wave at Saturn campaign is available at:

To view the MESSENGER images, visit:

Smallest planet discovery

An artist's conception of the tiny new planet Kepler-37b, which is slightly larger than Earth's moon and orbits its host star every 13 days. Photo: NASA

From Nature:

A sub-Mercury-sized exoplanet

20 February 2013

Since the discovery of the first exoplanets, it has been known that other planetary systems can look quite unlike our own. Until fairly recently, we have been able to probe only the upper range of the planet size distribution, and, since last year, to detect planets that are the size of Earth or somewhat smaller. Hitherto, no planets have been found that are smaller than those we see in the Solar System.

Here we report a planet significantly smaller than Mercury. This tiny planet is the innermost of three that orbit the Sun-like host star, which we have designated Kepler-37. Owing to its extremely small size, similar to that of the Moon, and highly irradiated surface, the planet, Kepler-37b, is probably rocky with no atmosphere or water, similar to Mercury.

See also here. And here.

NASA's artist's illustration compares the planets in the Kepler-37 system to the moon and planets in the solar system. Photo: NASA

Ice on planet Mercury

From Nature:

Stores of ice confirmed on Sun-scorched Mercury

MESSENGER finds evidence of pure water ice near planet’s north pole.

29 November 2012
Water ice is abundant in Mercury's dark polar craters. Photo NASA/Johns Hopkins Uni Applied Phys Lab/Carnegie Inst of Washington

Talk about a land of fire and ice. The surface of Mercury is hot enough in some places to melt lead, but it is a winter wonderland at its poles — with perhaps a trillion tonnes of water ice trapped inside craters — enough to fill 20 billion Olympic skating rinks.

The ice — whose long-suspected presence1 has now been confirmed by NASA’s orbiting MESSENGER probe — seems to be much purer than ice inside similar craters on Earth’s Moon, suggesting that the closest planet to the Sun could be a better trap for icy materials delivered by comets and asteroids. Three papers detailing the findings are published today in Science2, 3, 4.

Despite Mercury’s blistering 400 °C temperatures, the floors of many of its polar craters are in permanent shadow, because the planet’s rotational axis is perpendicular to its orbital plane, so its poles never tip towards the star. Indeed, radar pinged to the planet from Earth in the past 20 years has revealed bright regions1 near the poles consistent with metres-thick slabs of pure water ice.

But “radar does not uniquely identify water ice,” says David Lawrence, a planetary scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. Sulphur, for example, could have produced a similar radar signature.

Now, three different lines of evidence back the water-ice interpretation. Infrared laser pulses fired at the planet by MESSENGER’s Mercury Laser Altimeter have revealed bright regions inside nine darkened craters near the planet’s north pole2. These bright regions, thought to be water ice, line up perfectly with ultra-cold spots that, according to a thermal model of the planet that takes into account Mercury’s topography, should never be warmer than –170 °C3.

A third team, using MESSENGER’s Neutron Spectrometer, has spotted the telltale signature of hydrogen — which they think is locked up in water ice — in those same regions4. “Not only is water the best explanation, we do not see any other explanation that can tie all the data together,” says Lawrence, lead author of the spectrometer study.

So where did the water come from? The bright icy spots identified by MESSENGER’s laser are surrounded by darker terrain which receives a bit more sunlight and heat. The neutron measurements suggest that this darker area is a layer of material about 10 centimetres thick that lies on top of more ice, insulating it.

Dark materials

This darker material around the bright spots may be made up of complex hydrocarbons expelled from comet or asteroid impacts, says David Paige, a planetary scientist at the University of California, Los Angeles, and first author of  the thermal-model paper3.

Paige and his colleagues suggest that when these icy bodies slam into Mercury, their components migrate over time — by repeatedly vaporizing and precipitating — to the cooler poles, where they get stuck in the frigid polar craters.

But even there, sunlight will sometimes hit parts of the craters’ interiors, vaporizing the water ice and leaving behind ‘lag deposits’ of hydrocarbons that gradually become thicker and darker as they are chemically altered by sunlight.

Small impacts should have buried the surface if the ice were a billion years old, and the MESSENGER researchers believe it might be much younger than that, perhaps 50 million years old.

“The ice deposits we are looking at are not ancient,” says Paige.



  1. Slade, M. A., Butler, B. J. & Muhleman, D. O. Science 258, 635–640 (1992).

    Show context

  2. Neumann, G. A. et al. Science (2012).Show context
  3. Paige, D. A. et al. Science (2012).Show context
  4. Lawrence, D. J. et al. Science (2012).Show context

Mysterious Mercury and Planetary Pareidolia: Photos here.