European Association for Astronomy Education

Source: NASA/Cassini

Plumes spray water ice out of the surface of Enceladus.
Image credit: NASA/JPL/SSI.

Cassini spacecraft has discovered the best evidence yet for a large-scale saltwater reservoir beneath the icy crust of Saturn's moon Enceladus. The data came from the spacecraft's direct analysis of salt-rich ice grains close to the jets ejected from the moon.

Data from Cassini's cosmic dust analyzer show the grains expelled from fissures, known as tiger stripes, are relatively small and usually low in salt far away from the moon. But closer to the moon's surface, Cassini found that relatively large grains rich with sodium and potassium dominate the plumes. The salt-rich particles have an "ocean-like" composition and indicate that most, if not all, of the expelled ice and water vapor comes from the evaporation of liquid salt-water. The findings appear in this week's issue of the journal Nature.(read more)

Related link: ESA

Source: ESA

Two Galileo satellites.Image credits: © ESA - P. Carril

As Europe prepares for October’s launch of the first Galileo satellites, a worldwide ground network is being put in place. Contracts signed today at the Paris Air & Space Show cover satellite control and the systems needed to generate Galileo services.(read more)

Source: ESA

ESA Application for iPhone and iPad. Image credit: ESA.

Space in your pocket…and also on your tablet! The new ESA iPhone or iPad application, or ‘App’, can now deliver a wealth of information on ESA missions, videos, images and news updates, at your fingertips. (read more)

Source: NASA

Artist's impression of LRO.
Image credit: NASA.

NASA has declared full mission success for the Lunar Reconnaissance Orbiter (LRO). LRO changed our view of the entire moon and brought it into sharper focus with unprecedented detail.

NASA's Exploration Systems Mission Directorate (ESMD) operated the LRO spacecraft and its instruments during the one-year mission phase. Now that the final data from the instruments have been added to the agency's Planetary Data System, the mission has completed the full success requirements. The data system, which is publicly available, archives data from past and present planetary missions as well as astronomical observations and laboratory data.

The rich new portrait rendered by LRO's seven instruments is the result of more than 192 terabytes of data, images and maps, the equivalent of nearly 41,000 typical DVDs.(read more)

Source: ESA.

Reentry of a previous ATV. Image credit: ESA.

The Johannes Kepler ATV (Automated Transfer Vehicle) has undocked from the International Space. The Johannes Kepler ATV was responsible for the International Space Station's biggest increase in altitude to date, significantly improving the 417-tonne Station's orbital mileage through the next decade of scientific research.

During three intensive reboost manoeuvres, ATV Johannes Kepler raised the ISS altitude from around 345 km to about 380 km, where it will use far less fuel to maintain its orbit and cutting the amount of fuel that must be sent up in the coming years by almost half.

The ATV will now  reenter Earth’s atmosphere on today ending its mission in fiery destruction.

The summer solstice occurs exactly when the Earth's axial tilt is most inclined towards the sun at its maximum of 23° 26'. Though the summer solstice is an instant in time, the term is also colloquially used like Midsummer to refer to the day on which it occurs.The summer solstice occurs is on June, 21st in the Northern Hemisphere and on December 21st in the Southern Hemisphere.

On the Summer Solstice we can reproduce Eratosthenes experiment to measure Earth's perimeter.

Eartosthenes was chief librarian of the Libarary of Alexandria and he read many documents and found out that at the Ancient Egyptian city of Swenet (known in Greek as Syene, and in the modern day as Aswan) that is located near the tropic of Cancer on June there is a well where on certain day of the year the sunlight goes down to the bottom of the well. He knew that in Alexandria there was no day that the great Obelisk did not produce shadow and he measured the shadow angle on the day the Sun was directly above the well in Aswan. He needed to know the distance from the well in Aswan to Alexandria and there several different versions of how he found out its value. The most popular one is that he send a slave to measure it in footsteps. The value that he used in his calculations was 8000 stadia (1 egiptian stadium is about 157.5 m, though the exact size of the stadium is often a theme of discussion).

With this information he measured the circumference of the Earth without leaving Egypt.

Tomorrow teachers from all over the world will make measurements allowing them to reproduce this historical experiment. Learn more about this on the website of the project.

Link:

EAAE Eratosthenes Project

Source: Chandra X-Ray Observatory

Illustration of Baby Black Hole.
Image credit: NASA/CXC/A.Hobart.

A composite image from NASA's Chandra X-ray Observatory and Hubble Space Telescope (HST) combines the deepest X-ray, optical and infrared views of the sky. Using these images, astronomers have obtained the first direct evidence that black holes are common in the early Universe and shown that very young black holes grew more aggressively than previously thought. (read more)

Source: ESA

Conjunction: before, during and after.
Image credits: ESA/DLR/FU Berlin (G. Neukum).

Earlier this month, ESA’s Mars Express performed a special manoeuvre to observe an unusual alignment of Jupiter and the martian moon Phobos. The impressive images have now been processed into a movie of this rare event. (read more)

Source: ESA Online Videos

Over 1.5 million kilometres from Earth, ESA's Herschel space telescope has been observing the Universe for the last two years, studying the infrared radiation emitted by the coldest bodies in the cosmos. See the invisible in this edition of Space.

Source: NASA Announcement

Solar panels are already important for energy of Space missions.
Image credit: NASA.

NASA issued a Broad Agency Announcement (BAA) seeking proposals for mission concept studies of a solar electric propulsion system demonstration to test and validate key capabilities and technologies for future exploration missions.

Multiple studies have shown the advantages of using solar electric propulsion to efficiently transport heavy payloads from low Earth orbit to higher orbits. This concept enables the delivery of payloads to low Earth orbit via conventional chemical rockets. The use of solar electric propulsion could then spiral payloads out to higher energy orbits, including Lagrange point one, a potential assembly point in space between Earth and the moon. This approach could facilitate missions to near Earth asteroids and other destinations in deep space. (read announcement)

Source: ESA

SSA programme is enabling Europe to detect hazards to critical space infrastructure.
Image credits: ESA - P. Carrill.

The European Commission recently set out the EU's main space priorities, which include protection of Europe's space infrastructure. The affirmation spotlights ESA's Space Situational Awareness Preparatory Programme as a strategic European necessity and a cornerstone of Europe's future in space.(read more)

Source: National Geographic/Andrew Fazekas

Artist's impression of a star's accretion made by a black hole.
Image credits: Mark A. Garlick, University of Warwick

A huge "belch" of radiation from a supermassive black hole indicates that the cosmic monster recently devoured a star, scientists say.

Earlier this year astronomers spied a burst of high-energy gamma rays emanating from the center of a dwarf galaxy 3.8 billion light-years away. The odd flash, dubbed Sw 1644+57, is one is the brightest and longest gamma ray bursts (GRBs) yet seen. (read more)

Source: NASA/Voyager

Artist's concept shows NASA's two Voyager spacecraft exploring the heliosheath.
Image credits: NASA/JPL-Caltech

Scientists analyzing recent data from NASA's Voyager and Cassini spacecraft have calculated that Voyager 1 could cross over into the frontier of interstellar space at any time and much earlier than previously thought. The findings are detailed in this week's issue of the journal Nature.

Data from Voyager's low-energy charged particle instrument, first reported in December 2010, have indicated that the outward speed of the charged particles streaming from the sun has slowed to zero. The stagnation of this solar wind has continued through at least February 2011, marking a thick, previously unpredicted "transition zone" at the edge of our solar system. (read more)

A total lunar eclipse took place on June 15, 2011. This was a relatively rare central lunar eclipse, in which the center point of Earth's shadow passes across the Moon.

The path of the Lunar Eclipse of June 15th, 2011. Image credit: Tom Ruen / Wikipedia

The eclipse was visible all over Europe and in several other parts of the world. The path of the lunar eclipse is shown bellow.

Visibility map of the Lunar Eclipse of June 15th, 2011. Image credit: Fred Espenak / NASA / Wikipedia

Pictures have been taken all over Europe. We present you some of them bellow. Fortunately, this time the weather has cooperated with all interested observers. The eclipse schedule also allowed children all over Europe to observe the eclipse with their parents.

The Total Lunar Eclipse of June 15th, 2011, in Algarve. Image credit: Alexandre Costa

A close-up of the Total Lunar Eclipse of June 15th, 2011, in Algarve. Image credit: Alexandre Costa

The Total Lunar Eclipse of June 15th, 2011, in The Czech Republic. Image credit: Wespecz/Wikipedia

A close-up of the Total Lunar Eclipse of June 15th, 2011, in Montalbán de Cordoba, Spain. Image credit: Hameryko/Wikipedia.

A close-up of the Total Lunar Eclipse of June 15th, 2011, in Malta. Image credit: Leonard E. Mercer.

A close-up of the Total Lunar Eclipse of June 15th, 2011, in Hungary. Image credit: Gestrgangleri/Wikipedia.

A close-up of the Total Lunar Eclipse of June 15th, 2011, in Pisa, Italy. Image credit: @UgoRom via Twitter

This eclipse was the first of two such eclipses in 2011. The second will occur on December 10, 2011.

Tonight there will be a full Moon and a total lunar eclipse! We'll get a good view across Europe because the Moon starts to move into the Earth's shadow in early evening so this will be great for observations even with children.

The first lunar eclipse of 2011 occurs at the Moon's ascending node in southern Ophiuchus about 7° west of the Lagoon Nebula (M8). The Moon passes deeply through Earth's umbral shadow during this rather long event. The total phase itself lasts 100 minutes. The last eclipse to exceed this duration was in July 2000. The Moon's contact times with Earth's umbral and penumbral shadows are listed below.

• Penumbral Eclipse Begins: 17:24:34 UT
• Partial Eclipse Begins: 18:22:56 UT
• Total Eclipse Begins: 19:22:30 UT
• Greatest Eclipse: 20:12:37 UT
• Total Eclipse Ends: 21:02:42 UT
• Partial Eclipse Ends: 22:02:15 UT
• Penumbral Eclipse Ends: 23:00:45 UT

Click on the image to see a complete information sheet about the eclipse by Fred Espenak.

When totality begins the moon is expected to take on a reddish glow. It's a stunning sight and yep, you can look directly at it with no problem of hurting your eyes. It will be fun to take some pictures. If you want to, you can send them to us and we will publish them on our website.

Source: Chandra@University of Texas

Fornax Galaxy.
Image credit: David Malin/ Anglo-Australian Observatory

Astronomical observations show that everything that we have ever seen, including stars and planets, is a small fraction of what there is in the Universe. At least 90% of the Universe is made of something else - of dark matter (DM). We know that it exists only because its gravity pulls on the things we see. But it emits no known form of radiation, so we do not know what it is made of. Many possibilities have been proposed, including elementary particles left over from the Big Bang, underluminous or dead stars, and million-solar-mass black holes. The problem of DM - what it is and how it affects galaxy formation and evolution - is one of the most fundamental puzzles of astronomy.

Smaller galaxies are observed to be more dominated by dark matter. The smallest galaxies known are at least 99 % dark. These galaxies look incredibly gossamer, but they are really like cannonballs: they contain a much higher density of dark matter than do giant galaxies. These galaxies did not know when they formed that we would be able to discover them 10 billion years later only if they managed to hold onto 1 % of their mass in stars. Instead, when their first stars died in supernova explosions, they may in many cases have blown away so much of the remaining gas that too few stars were ever formed for us to find the empty halos that are left.

Smaller galaxies are also more numerous; tiny dSph galaxies outnumber large galaxies like our Milky Way. More of them continue to be discovered; clearly we have not found all of them. Since almost-dark galaxies are the most common ones known, darker galaxies may be more common still. (read source)

Source: Smithsonian Astrophysical Observatory (SAO)

Milky Way's new arm. Credit: T. Dame.

Our Milky Way galaxy, like other spiral galaxies, has a disk with sweeping arms of stars, gas, and dust that curve around the galaxy like the arms of a huge pinwheel. The Sun, Earth, and solar system are located in a spur of material that lies between two of the spiral arms, collectively orbiting around the galaxy about 25,000 light-years from its center.

Using a small 1.2-meter radio telescope on the roof of their science building in Cambridge, CfA astronomers Tom Dame and Pat Thaddeus used carbon monoxide emission to search for evidence of spiral arms in the most distant parts of the galaxy, and discovered a large new spiral arm peppered with dense concentrations of molecular gas. (read source)

Source: NASA/Dawn

Artist's impression of Dawn. Image credit: NASA.

Scientists working with NASA's Dawn spacecraft have created a new video showing the giant asteroid Vesta as the spacecraft approaches this unexplored world in the main asteroid belt.

The video loops 20 images obtained for navigation purposes on June 1. The images show a dark feature near Vesta's equator moving from left to right across the field of view as Vesta rotates. Images also show Vesta's jagged, irregular shape, hinting at the enormous crater known to exist at Vesta's south pole. (read more)

Source: MESSENGER Mission News

MESSENGER Spacecraft. Image credit: NASA/MESSENGER

Yesterday the MESSENGER spacecraft successfully completed the first of four “hot seasons” expected to occur during its one-year primary mission in orbit about Mercury. During these hot seasons, the Sun-facing side of the probe’s sunshade can reach temperatures as high as 350°C.

These hot conditions are the result of two concurrent circumstances, says MESSENGER Mission Systems Engineer Eric Finnegan, of the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. “Mercury is in an eccentric orbit, and its distance from the Sun varies over 88 days, from 43,689,229 miles to 28,816,300 miles,” he explains. “On May 13, Mercury began heading closer to the Sun in its orbit. The planet reached its closest distance from the Sun on June 12.”

The second contributor to this heat is the geometry of MESSENGER’s orbit relative to the hot dayside of Mercury. The spacecraft is in a highly eccentric orbit around the planet, approaching to within 310 miles of the surface every 12 hours.

“During this hot period, the closest point of approach of the spacecraft to Mercury’s surface occurs on the sunlit side of the planet, so for almost one hour per orbit the spacecraft must pass between the Sun on one side and the hot dayside surface of the planet on the other,” Finnegan says. “To add further extremes, this season is also when the spacecraft passes over the nightside of the planet at high elevations and experiences the longest solar eclipses of the mission. During this period, when eclipses last as long as 62 minutes per orbit, the solar arrays are not illuminated and the spacecraft must derive its power from its internal battery.”

High temperatures are always a risk to mechanical and electronic systems, and the geometry of this portion of the orbit severely constrains the ability of the spacecraft to cool itself by radiating heat to cold space. MESSENGER engineers have taken several steps to ensure that the spacecraft remains safe.

“We rotated the solar arrays off the Sun through some of the hottest points so they do not have a view to either the Sun or the hot, dayside surface of the planet,” Finnegan says. “We are power cycling some of the more sensitive instruments to reduce their internal heat dissipation. In a manner similar to the treatment of the solar arrays, we are also adjusting the attitude of the spacecraft to keep some of the more sensitive parts of the spacecraft from seeing the hottest parts of the planet’s surface.”

All of the instruments have been operating during this period. Finnegan says that there have been times during each orbit when instruments are turned off, however, mostly to conserve power during eclipses.

These conditions are expected to recur approximately every 88 days (i.e., the time it takes Mercury to orbit the Sun). MESSENGER can therefore look forward to three more hot seasons during the course of its primary mission.

Source: NASA-SWIFT

Markarian 739 in visible light.
Image credit: SDSS.

A study using NASA's Swift satellite and the Chandra X-ray Observatory has found a second supersized black hole at the heart of an unusual nearby galaxy already known to be sporting one.

The galaxy, which is known as Markarian 739 or NGC 3758, lies 425 million light-years away toward the constellation Leo. Only about 11,000 light-years separate the two cores, each of which contains a black hole gorging on infalling gas.

The study will appear in a forthcoming issue of The Astrophysical Journal Letters.(read more)