Spacecraft Cassini’s Saturn dive video


This video from the USA says about itself:

NASA: Cassini‘s First Fantastic Dive Past Saturn

3 May 2017

As NASA’s Cassini spacecraft made its first-ever dive through the gap between Saturn and its rings on April 26, 2017, one of its imaging cameras took a series of rapid-fire images that were used to make this movie sequence. The video begins with a view of the vortex at Saturn’s north pole, then heads past the outer boundary of the planet’s hexagon-shaped jet stream and continues further southward.

A detailed caption describing these video clips, and the unedited clips themselves, are available here. For more information about Cassini‘s Grand Finale, visit here.

The first Cassini to explore Saturn was a person. Space probe preparing to crash into ringed planet was named for an astronomical pioneer, by Tom Siegfried, 7:00am, May 15, 2017: here.

50 years ago, an Earth-based telescope spotted Saturn’s fourth ring: here.

Solar eclipse in August in the USA


This video says about itself:

22 August 2015

There will be a total eclipse of the Sun in the USA on Monday, 21 August 2017. This documentary explains how to view it very simply, in completely safely and without specialised equipment.

More information is here.

From Science News in the USA:

Read up on solar eclipses before this year’s big event

New books chronicle the science, history and cultural significance of these phenomena

By Sid Perkins

8:00am, April 30, 2017

In August, the United States will experience its first coast-to-coast total solar eclipse in nearly a century. Over the course of an hour and a half, the moon’s narrow shadow will slice across 12 states, from Oregon to South Carolina (SN: 8/20/16, p. 14). As many as 200 million people are expected to travel to spots where they can view the spectacle, in what could become one of the most watched eclipses in history. Excitement is building, hence the flurry of new books about the science, history and cultural significance of what is arguably one of Earth’s most awesome celestial phenomena.

Total solar eclipses happen when the moon passes in front of the sun as seen from Earth, and the moon blocks the entire face of the sun. This event also blocks sunlight that would otherwise scatter off the molecules in our atmosphere, reducing a source of glare and so allowing an unfettered view of the sun’s outer atmosphere, or corona. Total solar eclipses arise from a fluke of geometry that occurs nowhere else in the solar system, astronomer Anthony Aveni explains in In the Shadow of the Moon. Only Earth has a moon that appears, from the planet’s viewpoint, to fit so neatly over the sun — a consequence of the fact that the sun is a whopping 400 times as large as the moon but also 400 times farther away. Moons orbiting other planets are either too small to fully cover the sun’s face or are so large that they fully block any view of the corona.

In fact, the fluke of geometry is also a fluke of history: Because the moon’s orbit drifts about four centimeters farther from Earth each year, there will come a time when the moon will no longer appear to cover the sun, notes planetary scientist John Dvorak in Mask of the Sun. We already get a preview of that distant day: When the moon passes in front of the sun during the most distant portions of its orbit (and thus appears its smallest), Earth is treated to a ring, or annular, eclipse.

In the Shadow of the Moon, Mask of the Sun and physicist Frank Close’s Eclipse all do a good job of explaining the science behind total solar eclipses. That includes clarifying why one is seen somewhere on Earth once every 18 months or so, on average, instead of every time the moon crosses paths with the sun during the new moon. In short, it’s because the moon’s orbit is slightly tilted compared with Earth’s orbit around the sun, making the moon pass either above or below the sun during most new moons.

Many solar eclipses are preceded by a lunar eclipse about two weeks earlier — a coincidence that may have helped ancient astrologers “predict” an eclipse, Close writes. Additional observations, Dvorak notes, may have helped these nascent astronomers notice the long-term pattern in solar eclipses with similar paths, which tend to recur roughly every 18 years. While ancient Babylonians could predict the onset of a solar eclipse within a few hours — and ancient Greeks to within about 30 minutes — today’s astronomers can pin down eclipses to within a second.

That precision has fueled the craze of “eclipse chasing,” in which scientists and nonscientists alike trek to often remote regions to gather data or to simply experience the brief darkness — rarely more than seven minutes, and sometimes less than one second — of totality. In 1925, scientists chased an eclipse with an airship; in 1973, they did so at supersonic speed in a Concorde. All three books describe in detail various historical expeditions to view eclipses, everywhere from New York’s Central Park to exotic hot spots such as the South Pacific and Pike’s Peak in Colorado (which was pretty remote and exotic in 1878).

Each book shares many of the same anecdotes and recounts many of the same scientific breakthroughs that resulted from eclipse research. Both In the Shadow of the Moon and Mask of the Sun take readers on a largely chronological path through eclipse history. But their organizations differ slightly: The science of eclipses is deftly scattered throughout Mask of the Sun, while In the Shadow of the Moon addresses various scientific topics in wonderfully thorough chapters of their own.

Of this trio of books, Eclipse — more a memoir of Close’s lifetime fascination and personal experiences with eclipses than a detailed chronicle of historical lore — provides the most amusing and insightful descriptions of eclipse chasers. They are, Close writes, “an international cult whose members worship the death and rebirth of the sun at moveable Meccas, about half a dozen times every decade.”

A teacher kindled Close’s love of eclipses in 1954 when Close was an 8-year-old living north of London. He reached his 50s before experiencing a total eclipse (1999 in extreme southwestern England), but since then has seen a handful more, including from a cruise ship southwest of Tahiti and a safari camp in Zambia.

Who knows how many budding young scientists the Great American Eclipse of 2017 — or these books — will inspire.

Trump’s ‘illegal alien’ hotline gets calls on ‘criminal Martians’


This video from the USA says about itself:

Trump‘s ‘Crímínal Alíen’ Hotline Trolled With UFO Calls

30 April 2017

So, instead of the information on ‘illegal’ Mexicans, South Americans, Muslims etc. that Trump wanted, he gets calls on fictional ‘criminals’ from planet Mars, planet Plutarch, etc.

Planet Saturn, spectacular Cassini spacecraft photos


This video says about itself:

Closest Saturn Pics Yet Snapped During Daring Cassini Dive

27 April 2017

NASA’s Cassini spacecraft’s ’Grand Finale’ has begun with the first of 22 planned dives between Saturn‘s innermost rings and the planet itself. The probe came within about 1900 miles (3000 km) of the planet’s cloudtops and captured some amazing images.

Read more here.

From Science News:

Cassini’s ring dive offers first close-up of Saturn’s cloud tops

Spacecraft images reveal stunning views of planet’s hurricane and more

By Ashley Yeager

5:49pm, April 27, 2017

Cassini has beamed back stunning images from the spacecraft’s daring dive between Saturn and its rings.

The first closeup pictures of the planet’s atmosphere reveal peculiar threadlike clouds and puffy cumulus ones, plus the giant hurricane first spotted on Saturn in 2008 (SN: 11/8/08, p. 9). Released April 27, the images of Saturn’s cloud tops are a “big step forward” for understanding the planet’s atmosphere, says Cassini imaging team member Andy Ingersoll, an atmospheric scientist at Caltech.

“I was pretty struck by the prevalence of the filamentary type of clouds,” he says. “It’s as if the long threads of clouds refuse to mix with each other.” Studying the interactions of these clouds and the cumulus ones will reveal what’s going on in Saturn’s skies.

During its dive, Cassini swooped to within 3,000 kilometers of the planet’s atmosphere and 300 kilometers of the innermost edge of the rings at 124,000 kilometers per hour. Slamming into even tiny particles from the rings could have damaged the spacecraft. To protect Cassini, mission scientists used the spacecraft’s 4-meter-wide antenna as a shield, putting the spacecraft temporarily out of contact with NASA.

Cassini reestablished contact with mission control early on April 27 and started to send back data minutes later. Shots of the rings and other features will be available in the coming days, and more stunning views are expected when the spacecraft shoots through the gap between Saturn and its rings again on May 2. It will ultimately orbit 20 more times before plunging into the planet’s atmosphere on September 15 (SN Online: 4/21/17).

Cassini gallery of raw Saturn images: here.

Cassini spacecraft’s final planet Saturn research


This video from the USA says about itself:

Cassini‘s final orbits around Saturn | Science News

21 April 2017

In Cassini‘s last act, the spacecraft will whiz 22 times between Saturn and its rings. This animation illustrates the spacecraft’s final orbits. Read more here.

Metals discovered in atmosphere of planet Mars


This video says about itself:

11 April 2017

MAVEN makes first direct detection of the presence of metallic ions in the ionosphere.

Mars has electrically charged high-ion metal atoms in its atmosphere, according to new results from the NASA spacecraft MAVEN.

Metal ions may reveal previously invisible activity in the mysterious atmosphere charged electrically ionosphere of Mars. MAVEN has made the first direct detection of the permanent presence of metal ions in the ionosphere of a planet other than Earth.

Because metal ions have a long shelf life and are transported away from their region of origin by neutral winds and electric fields, they can be used to infer movement in the ionosphere, similar to the way we use a fluted leaf to reveal how the wind is blowing. Grebowsky is the lead author of an article on this research appears April 10 in Geophysical Research Letters.

MAVEN (Mars Environment and volatile Mission Evolution) is exploring the upper atmosphere of Mars to understand how the planet missed most of its air, transforming a world that could have endured a billion years ago life on a cold desert planet today. The understanding of ionospheric activity is shedding light on how the atmosphere of Mars is being lost to space, according to the team.

The metal comes from a constant rain of small meteorites on the red planet. When a high-velocity meteoroid strikes the atmosphere of Mars, it vaporizes. Metal atoms in the vapor wake get some of their electrons pulled out by other atoms and molecules charged in the ionosphere, transforming the metal atoms into electrically charged ions.

From Sci-News.com:

MAVEN Detects Metal Ions in Martian Atmosphere

Apr 11, 2017

NASA’s Mars Atmosphere and Volatile EvolutioN (MAVEN) mission has made the first detection of the continuous presence of iron, magnesium, and sodium ions in the electrically charged upper atmosphere (ionosphere) of the Red Planet.

Sounding rockets, radar and satellite measurements have detected metal ion layers high in the atmosphere above Earth.

There’s also been indirect evidence for metal ions above other planets in our Solar System.

When spacecraft are exploring these worlds from orbit, sometimes their radio signals pass through the planet’s atmosphere on the way to Earth, and sometimes portions of the signal have been blocked.

This has been interpreted as interference from electrons in the ionosphere, some of which are thought to be associated with metal ions.

However, long-term direct detection of the metal ions by MAVEN is the first conclusive evidence that these ions exist on another planet.

“MAVEN has detected iron (Fe+), magnesium (Mg+), and sodium (Na+) ions in the upper atmosphere of Mars over the last two years using its Neutral Gas and Ion Mass Spectrometer instrument, giving us confidence that the metal ions are a permanent feature,” said Dr. Joseph Grebowsky, a researcher at NASA’s Goddard Space Flight Center, and his colleagues from the United States and UK.

According to the team, the metal comes from a constant rain of tiny meteoroids onto the planet.

When a high-speed meteoroid hits the Martian atmosphere, it vaporizes. Metal atoms in the vapor trail get some of their electrons torn away by other charged atoms and molecules in the ionosphere, transforming the metal atoms into electrically charged ions.

“Observing metal ions on another planet gives us something to compare and contrast with Earth to understand the ionosphere and atmospheric chemistry better,” said Dr. Grebowsky, who is the lead author of a paper on this research published online in the journal Geophysical Research Letters on April 10.

“Because metallic ions have long lifetimes and are transported far from their region of origin by neutral winds and electric fields, they can be used to infer motion in the ionosphere, similar to the way we use a lofted leaf to reveal which way the wind is blowing.”

Dr. Grebowsky and co-authors also found that the metal ions behaved differently on Mars than on Earth.

Our planet is surrounded by a global magnetic field generated in its interior, and this magnetic field together with ionospheric winds forces the metal ions into layers.

However, Mars has only local magnetic fields fossilized in certain regions of its crust, and the authors only saw the layers near these areas.

“Elsewhere, the metal ion distributions are totally unlike those observed at Earth,” Dr. Grebowsky said.

Bubbles may put mysterious fizz in [Saturn moon] Titan’s polar sea, by Ashley Yeager. 11:00am, April 18, 2017: here.

Astronomical news update


This video says about itself:

The Event Horizon Telescope Update 02/19/17

An overview of the coming attempt to directly image the event horizon of a black hole using the The Event Horizon telescope.

Event Horizon Telescope to try to capture images of elusive black hole edge; by Emily Conover. 5:00am, April 5, 2017: here.

Massive red, dead galaxy spotted in young universe. Findings suggest need to reassess ideas about galaxy formation. By Ashley Yeager, 1:00pm, April 5, 2017: here.