Ultima Thule’s First Puzzle

Dec. 23, 2018: NASA’s New Horizons spacecraft is 12 million km from Ultima Thule and closing fast. On New Year’s Day, it will fly by the mysterious Kuiper Belt Object three times closer than it buzzed Pluto in 2015 revealing … no one knows what. In fact, the mysteries have already begun.

Long range images of Ultima Thule reveal that it has no light curve. In other words, its brightness is constant.


Above: An artist’s concept of Ultima Thule, a double-lobed object in the Kuiper Belt

“It’s really a puzzle,” says New Horizons Principal Investigator Alan Stern of the Southwest Research Institute. And here’s why:

Last year, astronomers watched a distant star pass behind Ultima Thule. Starlight winked in and out in a pattern suggesting an elongated object with two bulbous lobes. Ultima Thule could be a binary system. You would expect the reflected brightness of such an object to vary as it rotates in the sunlight. Yet Ultima Thule does not behave that way.

What’s going on? New Horizons science team members have different ideas. “It’s possible that Ultima’s rotation pole is aimed almost right at the spacecraft,” speculates Marc Buie of the Southwest Research Institute. Such an alignment, however, is unlikely.

“Another explanation,” says the SETI Institute’s Mark Showalter, “is that Ultima may be surrounded by a cloud of dust that obscures its light curve–much the same way that a comet’s coma often overwhelms the light reflected by its central nucleus.”

“A more bizarre scenario is one in which Ultima is surrounded by many tiny tumbling moons,” suggests University of Virginia’s Anne Verbiscer, a New Horizons assistant project scientist. “If each moon has its own light curve, then together they could create a jumbled superposition of light curves that make it look to New Horizons like Ultima has a small light curve.”

“It’s hard to say which of these ideas is right,” Stern says. “We’ll get to the bottom of this puzzle soon – New Horizons will swoop over Ultima and take high-resolution images on Dec. 31 and Jan. 1, and the first of those images will be available on Earth just a day later. When we see those high–resolution images, we’ll know the answer to Ultima’s vexing first puzzle. Stay tuned!”

GIFTS FROM THE EDGE OF SPACE: The students of Earth to Sky Calculus are about to kick off a new year of cosmic ray balloon launches, continuing a 5-year campaign to monitor increasing levels of radiation in Earth’s atmosphere. You can help. Buy any gift item from the Earth to Sky Store and we’ll give you 10% off to celebrate the New Year.

All items in the Earth to Sky Store have flown to the edge of space onboard cosmic ray balloons. Each one comes with a greeting card showing the item in flight and telling the story of its journey. All sales support the Earth to Sky Calculus cosmic ray ballooning program and hands-on STEM research.

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The Mystery of Ultima Thule

Dec. 31, 2018: When NASA’s New Horizons spacecraft flew past Pluto three years ago, mission scientists watching the first close-up images were shocked. Despite being stuck in the deep freeze of the Solar System 6 billion km from the sun, Pluto was not the frozen-stiff world many expected it to be. The geography of the dethroned 9th planet was alive with mountain ranges, windswept dunes, bladed terrain and much more. In one quick flyby, New Horizons turned planetary science on its head.

Get ready to be shocked again. New Horizons is just hours away from a new world even more mysterious than Pluto.


Above: A speculative artist’s concept of Ultima Thule with a small moon

Its name is “Ultima Thule” (2014 MU69), which means means “beyond the borders of the known world.” Indeed, the little space rock is profoundly unknown. Located almost a billion kilometers farther from the sun than Pluto, Ultima Thule has never been much more than a faint speck of light in telescopes. It inhabits the distant Kuiper Belt where, seemingly, almost anything is possible.

“Really, we have no idea what to expect,” says New Horizons principal investigator Alan Stern, of the Southwest Research Institute. “Will it have an atmosphere? Will it have rings? Will it have moons? Any of that could be possible, and soon we’ll know the answers.”

On New Year’s Eve and New Year’s Day, New Horizons will swoop three times closer to Ultima Thule than it flew past Pluto in July 2015, shattering previous records for the most distant body explored by a human spacecraft. First images will be posted on a web site set up by the New Horizons’ team: SeeUltimaThuleNow.com

We already know one thing about Ultima Thule. Its shape is elongated and strange. In 2017, astronomers watched a distant star pass behind Ultima Thule. Starlight winked in and out in a pattern suggesting two lobes with diameters of 20 and 18 km, respectively. Ultima Thule could be a small binary system.

“Ultima Thule is 100 times smaller than Pluto, but its scientific value is incalculable,” says Stern. “From everything we know, it was formed 4.5 or 4.6 billion years ago, 4 billion miles from the sun. It has been stored at that enormous distance from the sun, at a temperature of nearly absolute zero, ever since, so it likely represents the best sample of the ancient solar nebula ever studied.”

“Nothing like it has ever been explored,” he says.

China’s Mission to the Farside of the Moon

Dec. 8, 2018: China is going where no one has gone before–the farside of the Moon. At 2:23 am on Dec. 8th (local time in Sichuan province), a Long March 3B rocket blasted off from the Xichang Satellite Launch Centre, propelling a lander and rover toward the lunar farside. Zhou Kun photographed the launch:

“I took the picture only 500 meters away from the rocket,” says Kun. “The sound of the launch was tremendous and shocking. Three sets of 20-second exposures were used to render the rocket’s trajectory.”

From Earth, we can see only one side of the Moon. The other side, the lunar farside, is perpetually hidden from view. Apollo astronauts have flown over the farside of the Moon, and many satellites have photographed the Moon from behind–revealing it to be a rugged, heavily cratered landscape startlingly different from the side we typically see. But no one has ever landed there.

China’s Chang’e 4 mission aims to be the first. Reportedly, the lander will touch down inside a 186-kilometer-wide crater called Von Kármán. The crater is part of the South Pole–Aitken basin, the largest known impact structure in the Solar System. The Chang’e-4 rover will explore the landing site, probing it with ground-penetrating radar and measuring the mineral composition with an infrared spectrometer. If water is present, the rover might find it.


Above: An artist’s rendering of China’s Chang’e-4 lunar rover

And that’s just the beginning. The lander will also conduct experiments in lunar gardening. A small climate-controlled greenhouse in the lander will test whether potato and thale-cress (Arabidopsis) seeds can sprout and photosynthesize in low gravity without the twin protections of a thick atmosphere and magnetic field.

Communicating with the farside of the Moon is tricky. There’s no direct line of sight. To overcome this problem, on May 21, 2018, China launched a satellite named Queqiao (Chinese for “Magpie Bridge”) to relay signals between the lunar farside and Earth. Queqiao will be able to talk to ground stations in China, Argentina and Namibia, sending back radio signals and TV images. However, Chang’e 4 will have to perform the critical landing completely autonomously–a daring plan.

Landing is expected to occur early in the New Year, if successful catapulting the China National Space Administration to the forefront of lunar exploration. Stay tuned for updates and, meanwhile, congratulations to China for daring mighty things.

Realtime Space Weather Photo Gallery

CHRISTMAS GIFTS FROM THE EDGE OF SPACE: So far in 2018, the students of Earth to Sky Calculus have launched 42 space weather balloons to the stratosphere, measuring cosmic rays over 3 continents, 2 hemispheres, and 7 different US states. You can help them pay their helium bill by purchasing a Christmas gift from the edge of space:

Every item in the Earth to Sky Store has flown to the stratosphere alongside an array of cosmic ray sensors. Carried aloft by giant balloons, these unique gifts travel above 99.7% of Earth’s atmosphere, experiencing space-like blasts of cosmic rays, extreme cold, and a wild ride parachuting back to Earth after the balloon explodes. Even Amazon doesn’t carry items this far out!

Don’t forget to enter coupon code “SPACESANTA” at checkout for a 10% holiday discount.

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Voyager 2 Reaches Interstellar Space

Dec. 10, 2018: Voyager 2 has exited the sun’s magnetic bubble and entered interstellar space. Mission scientists announced the breakthrough yesterday at the American Geophysical Union meeting in Washington DC. Its twin, Voyager 1, crossed the same boundary in 2012, but Voyager 2’s crossing is arguably more significant because it carries a working instrument that can sense interstellar plasmas, providing the first in situ sampling of matter between the stars.

The most compelling evidence of Voyager 2’s exit from the heliosphere came from its onboard Plasma Science Experiment (PLS), an instrument that stopped working on Voyager 1 in 1980. Until recently, Voyager 2 was surrounded mainly by the solar wind–a type of plasma flowing outward from the sun. On Nov. 5th, Voyager 2’s plasma instrument observed a sharp decline in the solar wind, and since that date, it has observed no solar wind flow–a clear sign that the probe has left the heliosphere.

Replacing the solar wind is a blizzard of galactic cosmic rays. The sun’s magnetic field substantially protects the solar system from cosmic rays, fending off the high energy debris of supernova explosions in the Milky Way and elsewhere. Now that Voyager 2 has exited that protective shell, it is baldly exposed to cosmic rays, and its cosmic ray subsystem is registering a surge.

Launched in 1977, Voyager 2 now is slightly more than 11 billion miles (18 billion kilometers) from Earth. Mission operators still can communicate with Voyager 2 as it enters this new phase of its journey, but information – moving at the speed of light – takes about 16.5 hours to travel from the spacecraft to Earth.

The Voyager probes are powered using heat from the decay of radioactive material, contained in a radioisotope thermal generator (RTG). The power output of the RTGs diminishes by about four watts per year, which means that various parts of the Voyagers, including the cameras on both spacecraft, have been turned off over time to manage power. Thanks to these precautions, the Voyagers could continue to send back at least some data for years to come.

“There is still a lot to learn about the region of interstellar space immediately beyond the heliosphere,” said Ed Stone, Voyager project scientist based at Caltech in Pasadena, California. Stay tuned for updates from the stars.

Realtime Space Weather Photo Gallery

CHRISTMAS GIFTS FROM THE EDGE OF SPACE: So far in 2018, the students of Earth to Sky Calculus have launched 42 space weather balloons to the stratosphere, measuring cosmic rays over 3 continents, 2 hemispheres, and 7 different US states. You can help them pay their helium bill by purchasing a Christmas gift from the edge of space:

Every item in the Earth to Sky Store has flown to the stratosphere alongside an array of cosmic ray sensors. Carried aloft by giant balloons, these unique gifts travel above 99.7% of Earth’s atmosphere, experiencing space-like blasts of cosmic rays, extreme cold, and a wild ride parachuting back to Earth after the balloon explodes. Even Amazon doesn’t carry items this far out!

Don’t forget to enter coupon code “SPACESANTA” at checkout for a 10% holiday discount.

Far Out Gifts: Earth to Sky Store
All sales support hands-on STEM education

A Big Hole in the Sun’s Atmosphere

Dec. 6, 2018:  A large hole in the sun’s atmosphere is facing Earth and spewing a stream of solar wind in our direction. NASA’s Solar Dynamics Observatory is monitoring the structure, shown here in a false-color UV image taken on Dec. 6th:

The hole (technical term: “coronal hole”) is so large it almost completely bisects the solar disk, stretching more than a million km across the sun’s equator.

We’ve seen this coronal hole before. It has been spinning around with the sun, lashing Earth with solar wind approximately once a month since September. Last month, the lashing commenced on Nov. 9th, lasted for almost 3 days, and caused sharp tremors in the geomagnetic field. Solar winds blowing faster than 600 km/s sparked an explosion of Phoenix-shaped auroras over Norway:

“The display over Senja, Norway, on Nov. 11th was nothing short of magical,” recalls photographer Adrien Mauduit. “Huge colorful pillars took the shape of a fiery bird.”

The same stream of solar wind will return on Dec. 8th or 9th and it may be even more potent this time because the underlying coronal hole has hrown larger in the intervening month. Arctic sky watchers, mark your calendars and warm your cameras. The Phoenix might rise again. Free: Aurora Alerts.

Realtime Aurora Photo Gallery

ZEN ASTRONAUT: Are the holidays stressing you out? Get your zen from the edge of space. On Dec. 2, 2018, the students of Earth to Sky Calculus launched a cosmic ray balloon to the stratosphere. This meditating spaceman pendant went along for the ride:

The students are selling the pendants to support their ballooning program. You can have one for $129.95. They make great gifts for space fans and are guaranteed to soothe holiday stress. Each premium stainless steel pendant comes with a greeting card showing the astronaut in flight and telling the story of its journey to the edge of space and back again.

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A Comet as Big as the Full Moon

Dec. 4, 2018: On Dec. 16th, Comet 46P/Wirtanen will approach Earth less than 11.5 million km away–making it one of the 10 closest-approaching comets of the Space Age. It’s a small comet, with a nucleus barely 1 km wide, but such proximity makes even a small things appear large. The comet’s gaseous atmosphere is now as wide as a full Moon. Mike Broussard of Perry, Louisiana, photographed the comet on Dec. 2nd and inserted the Moon for scale:

“The comet still has a couple of weeks before closest approach and it is already as big as a full Moon,” says Broussard, who could see the comet with his naked eye–“just barely using averted vision and only when it was in the darkest section of the sky,” he adds.

Despite its close approach, 46P/Wirtanen will never become a Great Comet like Comet Hayakutake in 1996 or Comet Hale-Bopp in 1997. Wirtanen’s relatively small core of dirty ice cannot produce enough gas and dust to create a really bright, flamboyant tail. The best case scenario is probably a big diffuse cloud of magnitude +3 or +4, barely visible to the unaided eye but an easy target for binoculars and small wide-field telescopes.

Last night in Cape Cod, Massachusetts, photographer Chris Cook didn’t even need a telescope to capture Wirtanen’s green glow. He took this picture using a Canon 6D digital camera with a 35 mm lens:

“This was my first sighting of Comet 46P/Wirtanen–just under naked eye visibility for my skies, but in 7×50 binoculars I could see a very large coma (ball of gas) almost 1° in diameter!” reports Cook. “It reminds me of Comet Hayakutake’s massive coma but not nearly as bright.”

Celebrated astrophotographer Juan Carlos Casado, who last night took his own HDR image of the comet above a church tower in Spain, offers some advice to novices: “Use Raw file format, a fast lens (at least f/2.8) and ISO settings between 1600 and 3200. The exposure will depend on the focal length. I normally use the 500 rule–that is, exposure = 500 / focal (mm) with a tripod. It also helps in areas with light pollution to use an antipollution filter. I am now using Optolong L-Pro clip filter which gives excellent color balance.”

On the nights of closest approach, 46P/Wirtanen can be found in the constellation Taurus rising in the east at sunset and high in the sky at midnight. Sky watchers in the northern hemisphere may orient themselves using these sky maps: Dec. 5, Dec. 6, Dec. 7, Dec. 8, Dec. 9, Dec. 10, Dec. 11, Dec. 12, Dec. 13, Dec. 14, Dec. 15, Dec. 16

More resources: orbital elements; ephemeris; 3D orbit; light curve.

Hyperactive Comet Approaches Earth

Nov. 26, 2018: Small but hyperactive Comet 46P/Wirtanen is approaching Earth and could soon become visible to the naked eye. On Dec. 16th, the kilometer-wide ball of dirty ice will be less than 11.5 million km away–making it one of the 10 closest-approaching comets of the Space Age. It already looks magnificent through amateur telescopes. On Nov. 26th, Gerald Rhemann took this picture using a 12-inch reflector in Farm Tivoli, Namibia:

“The comet is currently gliding through the southern constellation Fornax,” says Rhemann. “If you look carefully at the image, you can see galaxy NGC 922 near the comet’s head, and another galaxy ESO 479-2 on the left.”

Rhemann says that the comet’s emerald green atmosphere is 50 arcminutes wide. In other words–almost twice as wide as a full Moon. Its apparent diameter could double in the weeks ahead as the comet comes even closer. Because Wirtanen’s brightness is spread over such a wide area, it is diluted just below the limit of naked eye visibility, with a current magnitude near +6.0. We don’t yet know if the comet will ultimately become visible to the unaided eye–but it will certainly be an easy target for binoculars and backyard telescopes in December.

The nucleus of 46P/Wirtanen is small (~1 km) compared to greater comets such as Hale-Bopp (~30 km) and Halley (~15 km). It makes up for this deficit by hyperactivity. Recent measurements show that the core of 46P/Wirtanen is spinning once every 8.9 hours and spewing almost 1028 water molecules every second. This exceeds the expected production of such a small comet.

Comet Wirtanen passes through the inner solar system every 5.4 years. Right now it is just below the orbit of Earth, and the gap is narrowing. Click on the image above to explore the comet’s approach, courtesy of NASA/JPL.

More resources: sky map; ephemeris; 3D orbit; light curve.

Realtime Comet Photo Gallery

Martian Cubesats to Broadcast Mars Landing

Nov. 25, 2018: For the first time ever, cubesats are approaching Mars. Their mission: To experience 7 minutes of terror. If all goes as planned, on Monday the two tiny spacecraft will watch NASA’s InSight lander touchdown on the Red Planet, relaying updates to Earth in near-real time.

PIA22316_hires_crop

InSight is the latest NASA probe to land on Mars–or disintegrate in the attempt. On Nov. 26th, it will tear through the planet’s atmosphere in a fireball, shedding more than 12,000 mph of velocity in just under 7 minutes. NASA hopes InSight will touchdown gently on the plains of Elysium Planitia where it can drill into Mars, using seismometers, heat flow sensors, and radios to study the planet’s interior.

Officially the two cubesats are known as MarCO-A and MarCO-B, but JPL engineers have nicknamed them “WALL-E” and “Eva.” They were launched alongside the lander on May 5, 2018. Mission controllers weren’t even sure the tiny spacecraft would survive the journey across interplanetary space–but they did. Now they will act as radio relay stations. Instead of waiting several hours for InSight to report back to Earth, WALL-E and Eva will relay entry, descent and landing data much sooner. This is the first time cubesats have traveled beyond Earth orbit, so it will be a significant achievement if they succeed.

NASA will broadcast the landing on NASA TV starting at 2 p.m. EST on Monday, Nov. 26th. Tune in here.

Realtime Space Weather Photo Gallery

Quiet Sun Makes “Musical Waves” in Earth’s Magnetic Field

Nov. 23, 2018: When a stream of solar wind hits Earth, magnetometers around the Arctic Circle normally go haywire, their needles swinging chaotically as local magnetic fields react to the buffeting of the solar wind. On Nov. 18th, however, something quite different happened. Solar wind hit Earth and produced … a pure, almost-musical sine wave:

Rob Stammes recorded the event from the Polarlightcenter, a magnetic observatory in the Lofoten Islands of Norway. “A very stable ~15 second magnetic oscillation commenced and persisted for several hours,” he says. “The magnetic field was swinging back and forth by 0.06 degrees, peak to peak, with the regularity of a metronome.”

Imagine blowing across a piece of paper, making it flutter with your breath. The solar wind can have a similar effect on magnetic fields. The waves Stammes recorded are essentially flutters propagating down the flanks of Earth’s magnetosphere excited by the breath of the sun. Researchers call them “pulsations continuous” — or “Pc” for short.

“A very sensitive magnetometer is required to record these delicate waves,” says Stammes. “I use a mechanical magnetometer with bar magnets suspended from a special wire. LEDs and light detectors in an isolated dark box record the motion of the magnets, while vanes in oil damp out non-magnetic interference.”

Pc waves are classified into 5 types depending on their period. The waves Stammes recorded fall into the range 15 to 45 seconds–that is, Pc3. Researchers have found that Pc3 waves sometimes flow around Earth’s magnetic field and cause a “tearing instability” in our planet’s magnetic tail. This, in turn, can set the stage for an explosion as magnetic fields in the tail reconnect.

A quartet of NASA spacecraft recently flew through just such an explosion. Last week, researchers from the University of New Hampshire reported that four Magnetospheric Multiscale (MMS) spacecraft spent several seconds inside a magnetic reconnection event as they were orbiting through Earth’s magnetic tail. Sensors on the spacecraft recorded jets of high energy particles emerging from the blast site. One jet was aimed squarely at Earth and probably sparked auroras when it hit the upper atmosphere.

Stammes has recorded many Pc waves in the past, “but this is the first time I have detected category Pc3,” he says. “This was a very rare episode indeed.”

Realtime Space Weather Photo Gallery

A Sunspot from the Next Solar Cycle

Nov. 19, 2018: Over the weekend, a small sunspot materialized in the sun’s northern hemisphere, then, hours later, vanished again. Such an occurrence is hardly unusual during solar minimum when sunspots are naturally small and short-lived. However, this ephemeral spot was noteworthy because its magnetic field was reversed–marking it as a member of the next solar cycle.

Shown above is a magnetic map of the sun from NASA’s Solar Dynamics Observatory on Nov. 17th. Two sunspot groups visible at 21:00 UT are inset.

Note sunspot AR2727 just north of the sun’s equator. It is a member of decaying Solar Cycle 24, the cycle that peaked back in 2012-2014. Next, compare its magnetic polarity to that of the other, unnumbered sunspot high above it. They are opposite. According to Hale’s Law, this means the two sunspots belong to different solar cycles. The high latitude sunspot appears to be a harbinger of Solar Cycle 25.

Solar cycles always mix together at their boundaries. Indeed, ephemeral sunspots possibly belonging to Solar Cycle 25 have already been reported on Dec. 20, 2016, and April 8, 2018. Now we can add Nov. 17, 2018, to list. The slow transition between Solar Cycle 24 and Solar Cycle 25 appears to be underway.

What does this mean? First, it suggests that the solar cycle is still operative. This contradicts widespread internet buzz that a Grand Minimum is in the offing, with no new sunspots expected for decades as the solar cycle grinds to a halt. Second, if patterns of previous solar cycles hold, Solar Minimum is not finished. It will probably continue to deepen in the year or so ahead even as new Solar Cycle 25 sunspots occasionally pop up, promising an ultimate end to the lassitude.