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.

The 2018 Leonid Meteor Shower

Nov. 16, 2018: Earth is entering a stream of debris from comet Tempel-Tuttle, source of the annual Leonid meteor shower. Last night, NASA’s network of all-sky meteor cameras detected five Leonid fireballs over the USA, numbers that will grow as we enter the weekend. Forecasters expect the shower to peak on Nov. 17th and 18th with rates as high as 15 meteors per hour.

The Leonids are famous for storming. As often as a few times each century, Earth hits a dense filament of Comet Tempel-Tuttle’s dusty debris, causing thousands of meteors per hour to stream out of the constellation Leo. Such a display in 1833 kickstarted modern meteor astronomy with an outburst of 100,000 Leonids per hour. Many readers still remember the Leonid fireballs of 1998 and the meteor storms of 1999, 2001 and 2002.

2018 is not a storm year, however. Earth will thread the needle between dense filaments, scooping up a lesser amount of dust. Each speck will hit Earth’s upper atmosphere at ~72 km/s (160,000 mph) producing a swift meteor emerging from the constellation Leo. The best time time to look is during the hours before dawn on Saturday, Nov. 17th, and Sunday, Nov. 18th, when the Lion is high in the southeastern sky.

If you do set your alarm for dawn, there’s more to see besides Leonids. For one thing, amateur astronomers have just discovered a new comet in the constellation Virgo. Comet Machholz-Fujikawa-Iwamoto (C/2018 V1) is an easy target for backyard telescopes, shining like a green fuzzy star of 8th magnitude. Use these orbital elements to point your optics.

Not far from the comet, Venus is having a close encounter with the brightest star in Virgo, Spica. Alan Dyer photographed the pair rising over the plains of Alberta, Canada, yesterday morning:

“Venus and Spica rose together as morning stars in the dawn twilight on Nov. 15th,” says Dyer. “Light clouds added the natural glows and enlarged Venus, so it really does look ‘big’ here!”

Amateur Astronomers Discover a Bright New Comet

Nov. 12, 2018: There’s a new comet in the morning sky. Discovered just last week by three amateur astronomers–one in Arizona and two in Japan–Comet Machholz-Fujikawa-Iwamoto (C/2018 V1) has quadrupled in brightness over the past few days. “It is now glowing like a fuzzy 8th magnitude star in the constellation Virgo,” reports Michael Jäger of Turmkogel, Austria, who photographed it on Nov. 11th:

“The discovery of a comet by amateur astronomers is a rare event nowadays because robotic Near-Earth-Object search programs usually catch them first,” he says. “My special congratulations to the three discoverers.”

Comet Machholz-Fujikawa-Iwamoto appears to be a first-time visitor to the inner solar system. It is plunging toward the sun on nearly-parabolic orbit that will take it just inside the orbit of Mercury. Closest approach to the sun (0.38 AU) is on Dec. 3-4; closest approach to Earth (0.67 AU) is Nov. 27th.


Click to view the comet’s 3D orbit

Fresh comets like this one are notoriously unpredictable. They can surge in brightness, seeming to promise a spectacular display, when suddenly they fizzle as fragile deposits of ice are exhausted by solar heat. No one knows if Comet Machholz-Fujikawa-Iwamoto will even become a naked eye object. At the moment it is an easy target for backyard telescopes with the promise of … unpredictability. Stay tuned!

Resources: 3D Orbit; Ephemeris; Orbital Elements; Sky Maps.

Realtime Comet Photo Gallery

Space Weather in Wartime: A Sunspot Detonates Naval Mines

Nov. 9, 2018: Rewind almost 50 years. On Aug. 2nd, 1972, giant sunspot MR11976 began to explode. For the next 2 days it unleashed a series of X-class flares, causing deep radio blackouts on Earth and punishing the solar panels and onboard electronics of satellites in Earth orbit. One CME (cloud of plasma) rocketed across the sun-Earth divide in only 14.6 hours–a record that still stands today. Resulting geomagnetic storms sparked auroras so bright, they cast shadows in countries as far south as Britian.


Above: Images of giant sunspot MR11976 from the Paris Observatory. [more]

The 1972 solar storm is legendary at NASA because it occurred in between two Apollo missions: the crew of Apollo 16 had returned to Earth in April and the crew of Apollo 17 was preparing for a moon landing in December. If the timing had only been a little different, astronauts could have been sickened by radiation, requiring an emergency return home for medical attention.

Turns out, it’s legendary in the Navy, too. According to a research paper just accepted for publication in the journal Space Weather, declassified Naval archives reveal an extraordinary explosion in the sea lanes near Vietnam: “On 4 August (1972) TF-77 aircraft reported some two dozen explosions in a minefield near Hon La over a 30-second time span…Ultimately the Navy concluded that the explosions had been caused by the magnetic perturbations of solar storms, the most intense in more than two decades.”


Above: A magnetogram from Manilla reveals unusual disturbances on Aug. 4-5, 1972. [more]

The authors, led by Delores Knipp of the University of Colorado, continue: “Aerial inspections revealed additional evidence of detonations elsewhere along the coast. The wartime memoirs of a US Navy Mineman-Sailor, Chief Petty Officer Michael Gonzales,state: ‘During the first few weeks of August, a series of extremely strong solar flares caused a fluctuation of the magnetic fields, in and around, South East Asia. The resulting chain of events caused the premature detonation of over 4,000 magnetically sensitive [mines].'”

This prompted the Navy to fast-track the replacement of magnetic-influence-only mines with mines that also required seismic or acoustic triggers during periods of high solar activity.

The August 1972 storms affected Earth in ways that are are only now being fully understood almost 50 years later. Moreover, Knipp and colleagues say the storms could be a previously-unrecognized example of an extreme Carrington-class event, and they urge further scrutiny. Given the experience of the US Navy, who can argue? Read the original research here.

Did an Alien Light Sail just Visit the Solar System?

Nov. 6, 2018: It sounds like a tabloid headline, but in this case it could be real. Mainstream researchers from the Harvard Center for Astrophysics have made the case that interstellar asteroid ‘Oumuamua could in fact be an alien light sail. Their original research was posted Oct. 31st on the moderated preprint server arXiv.org.

The story of ‘Oumuamua begins in October 2017 when it was discovered by Robert Weryk using the Pan-STARRS telescope atop Hawaii’s Haleakalā volcano. Astronomers quickly realized that ‘Oumuamua was something special: The object was hurtling through the Solar System on an unbound “hyperbolic” orbit. It came from the stars. Dramatic changes in the object’s brightness suggested that it was tumbling and asymmetric–thin and wide like a cigar or perhaps a pancake.

oumuamua

This artist’s concept shows how ‘Oumuamua is usually depicted: as a cigar shaped asteroid.

On its way out of the Solar System, something unexpected happened. ‘Oumuamua accelerated as if jets of gas were pushing it forward. Astronomers who initially thought ‘Oumuamua was an asteroid now turned their attention to the comet hypothesis. Comets naturally develop jets after close approaches to the sun, and such jets could explain ‘Oumuamua’s behavior.

Just one problem: “Despite its close Solar approach of only 0.25 AU (inside the orbit of Mercury), ‘Oumuamua shows no sign of any cometary activity, no cometary tail, nor gas emission/absorption lines,” point out the Harvard researchers Shmuel Baily and Abraham Loeb. Moreover, “if outgassing was responsible for the acceleration, then the associated torques would have driven a rapid evolution in ‘Oumuamua’s spin, incompatible with observations.”

So if it’s not an asteroid, and it’s not a comet, what could it be? Loeb, who is the chair of the astronomy department at Harvard University and also chairs the advisory board for the Breakthrough Starshot light sail project, realized that the acceleration profile was key. The non-gravitational acceleration of ‘Oumuamua scaled with distance from the sun (r) as r-2 — just like a light sail would behave.

comethypothesis

The comet hypothesis. Credit: NASA/JPL-Caltech

Modeling ‘Oumuamua as a thin object pushed by solar radiation pressure, Baily and Loeb found that it would fit the observations if it were a sheet of material 0.3 mm to 0.9 mm in thickness with a mass surface density of ~0.1 grams per square cm. “Although extremely thin, such an object would survive an interstellar travel over Galactic distances of  about 5 kiloparsecs, withstanding collisions with gas and dust-grains as well as stresses from rotation and tidal forces,” they wrote.

The researchers are now calling for more observations to look for ‘Oumuamua-like visitors to the Solar System. They could be natural objects created by some unknown process in the interstellar medium–or they might be artificial. “A survey for lightsails as technosignatures in the Solar System is warranted, irrespective of whether ‘Oumuamua is one of them,” they conclude.

Although technical, Baily and Loeb’s paper is well written and unusually readable for nonspecialists. Check it out.

Introducing the Thermosphere Climate Index

Oct. 26, 2018: The Thermosphere Climate Index (TCI) is now on Spaceweather.com. TCI is a relatively new space weather metric that tells us how the top of Earth’s atmosphere (or “thermosphere”) is responding to solar activity. During Solar Max the top of our atmosphere heats up and expands. Right now the opposite is happening. Solar minimum is here and the thermosphere is cooling off:

TCI_Daily_NO_Power_Percentiles_26oct18_yah2

TCI was invented by Martin Mlynczak of NASA’s Langley Research Center and colleagues. For the past 17 years they have been using the SABER instrument onboard NASA’s TIMED satellite to monitor the wattage of infrared emissions from the top of the atmosphere. Recently, they realized that these measurements could be used to summarize the state of the thermosphere in a single daily number–the TCI.  Moreover, they learned to calculate TCI going back in time all the way to the 1940s, thus placing current conditions in a historical context.

So where do we stand? Right now TCI=4.6×1010 W. That means the top of Earth’s atmosphere is approximately 10 times cooler than it was during the record-setting Solar Max of 1957-58 (TCI=49.4×1010 W). The record low value for TCI, 2.1×1010 W, was set during the Solar Minimum of 2009. It’s still not that cold in the thermosphere, although we’re getting close.

You can monitor daily values of TCI on SpaceWeather.com. It’s located here:

righthere

Not only does the number track the slow progression of the 11-year solar cycle, but also it can change suddenly in response to solar flares and geomagnetic storms. As these events occur, we’ll be writing about them to raise awareness of the many ways the sun can dump energy into Earth’s atmosphere.

Finally, please be aware that the thermosphere is very far above our heads–more than 100 km high. Just because the rarefied air up there is cooling off, it doesn’t mean the surface of the Earth is getting colder. Not yet, at least. Stay tuned for updates as the solar cycle progresses.

Atmospheric Radiation Increasing from Coast to Coast in the USA

Oct. 24, 2018: So you thought Solar Minimum was boring? Think again. High-altitude balloon flights conducted by Spaceweather.com and Earth to Sky Calculus show that atmospheric radiation is intensifying from coast to coast over the USA–an ironic result of low solar activity. Take a look at the data:

atmospheric_radiation2

Above: Radiation dose rates at the Regener-Pfotzer Maximum, ~65,000 ft high at the entrance to the stratosphere.

Since 2015, we have been monitoring X-rays, gamma-rays and neutrons in the stratosphere–mainly over central California, but also in a dozen other states (NV, OR, WA, ID, WY, KS, NE, MO, IL, ME, NH, VT). Everywhere we have been there is an upward trend in radiation–ranging from +20% in central California to +33% in Maine. The latest points, circled in red, were gathered during a ballooning campaign in August-October 2018.

How does Solar Minimum boost radiation? The answer lies in the yin-yang relationship between cosmic rays and solar activity. Cosmic rays are the subatomic debris of exploding stars and other violent events. They come at us from all directions, 24/7. Normally, the sun’s magnetic field and solar wind hold cosmic rays at bay–but during Solar Minimum these defenses weaken. Deep-space radiation surges into the solar system.

sunspotnumbers_oct2018

Cosmic rays crashing into our planet’s atmosphere produce a spray of secondary particles and photons. That secondary spray is what we measure. Each balloon flight, which typically reaches an altitude greater than 100,00o feet, gives us a complete profile of radiation from ground level to the stratosphere. Our sensors sample energies between 10 keV and 20 MeV, spanning the range of medical X-ray machines, airport security devices, and “killer electrons” in Earth’s radiation belts.

Who cares? For starters, anyone who flies. Cosmic radiation at aviation altitudes is typically 50 times that of natural sources at sea level. Pilots are classified as occupational radiation workers by the International Commission on Radiological Protection (ICRP) and, according to a recent study from researchers at the Harvard School of Public Health, flight attendants face an elevated risk of cancer compared to members of the general population. They listed cosmic rays as one of several risk factors. Weather and climate may also be affected, with some research linking cosmic rays to to the formation of clouds and lightning. Finally, there are studies (one recently published in Nature) asserting that heart rate variability and cardiac arrhythmias are affected by cosmic rays in some populations. If true, it means the effects reach all the way to the ground.

As 2018 comes to an end, Solar Minimum appears to be just getting started. Cosmic rays could continue to increase for years to come, so stay tuned.

Realtime Space Weather Photo Gallery

Inferior Conjunction of Venus

Oct. 22, 2018: On Oct. 26th, Venus will pass almost directly between Earth and the sun–an event astronomers call “inferior solar conjunction.” As Venus approaches the sun, the planet is turning its night side toward Earth, reducing its luminous glow to a thin sliver. Shahrin Ahmad of Kuala Lumpur, Malaysia, took this picture on Oct. 19th:

“I took this picture in broad daylight,” says Ahmad. “Venus was really big in the eyepiece of my telescope–almost a full arcminute in diameter. And the crescent shape was easily visible in the 8×50 finder scope.”

In the days ahead, the crescent of Venus will become increasingly thin and circular. The horns of the crescent might actually touch when the Venus-sun angle is least (~6 degrees) on Oct. 26th. This is arguably the most beautiful time to observe Venus, but also the most perilous. The glare of the nearby sun magnified by a telescope can damage the eyes of anyone looking through the eyepiece.

Anthony J. Cook of the Griffith Observatory has some advice for observers: “I have observed Venus at conjunction, but only from within the shadow of a building, or by adding a mask to the front end of the telescope to fully shadow the optics from direct sunlight. This is tricky with a refractor or a catadioptric, because the optics start at the front end of the tube. Here at Griffith Observatory, I rotate the telescope dome to make sure the lens of the telescope is shaded from direct sunlight, even through it means that the lens will be partially blocked when aimed at Venus. With our Newtonian telescope, I add a curved cardboard mask at the front end of the tube to shadow the primary mirror.”

Earlier today, Richard Nugent of Framingham, Massachusetts, used a 10-inch telescope (masked down to 60 mm) and an iPhone 8Plus to photograph Venus in broad daylight:

“Venus is 1.3% illuminated and only 9°20′ from the sun!” says Nugent.

Realtime Venus Photo Gallery

The Orionid Meteor Shower

Oct. 19, 2018: Right now, specks of dust from Halley’s Comet are disintegrating in Earth’s atmosphere, kicking off the annual Orionid meteor shower. NASA cameras caught more than a dozen Orionid fireballs streaking across the USA during the past 48 hours, and the show is expected to improve during the weekend as Earth moves deeper into Halley’s stream of debris:

fireball_strip2

Above: This Orionid fireball, observed by Maciek Myszkiewicz in Oct. 2012, was as bright as a full Moon.

“The upcoming Orionids should provide a fairly good show for most visual observers,” says Peter Brown of the University of Western Ontario Meter Physics Group. “The shower’s radiant is already quite active and well defined in data from the Canadian Meteor Orbit Radar (CMOR).”

Orionids appear every year around this time when Earth crosses Halley’s debris stream, with the shower typically producing about 20 meteors per hour. Some of the brightest stars and constellations in the sky–e.g., Orion the Hunter, Sirius the Dog Star, and Taurus the Bull–form the shower’s backdrop. This makes the display extra-beautiful in disproportion to the raw number of meteors.

Some years, however, are even better than others. “Most notable was a short-lived outburst of relatively bright Orionids in 1993 observed several days before the predicted peak. This hints that there may be narrow filaments of larger meteoroids embedded in the overall debris stream,” says Brown. “We also observed enhanced Orionid activity in the years 2006 through 2009 with rates 2 to 3 times normal.”

This year’s shower has one thing going against it: The nearly full Moon. Lunar glare could reduce visible meteor rates 2- or 3-fold. The best time to look, therefore, is during the dark hours before sunrise when the Moon is sinking below the western horizon and the shower’s radiant in Orion is high in the southeast: sky map.

“Finding dark skies and clear weather in the early morning hours of Sunday, Oct 21st, just after the moon sets this year is the surest way to see these messengers from 1P/Halley,” says Brown. Enjoy the show!

Realtime Meteor Photo Gallery

 

Geomagnetic Thunder? Auroras Caught Making Noise

Oct. 10, 2018: On Oct. 7th, a solar wind stream hit Earth’s magnetic field, sparking a G1-class geomagnetic storm. In southern Finland, the night sky turned green as energetic particles rained down on the upper atmosphere. But there was more to the show than beautiful lights.

“The storm also produced a number of distinctive sounds including crackles and claps,” reports Prof. Emeritus Unto K. Laine of Finland’s Aalto University. “Here is a recording of one of the strongest sounds of the night–a sharp clap.” Click to listen:

“I recorded this in the vicinity of Fiskars village after midnight local time,” he says.

Auroral sounds are controversial. Over the centuries, there have been many reports of strange sounds under the Northern Lights. However, researchers have struggled to explain the phenomenon and sometimes suggested that they might be imaginary. Laine is a believer: “We have been recording sounds like these for almost 20 years as part of the Auroral Acoustics Project.” More samples may be found here.

Laine has developed arrays of microphones that can pinpoint the sounds through triangulation. He finds that they occur about 70 meters above the ground. Temperature inversion layers at that altitude can cause a separation of + and – charges in the air. During some geomagnetic storms, the charge separation breaks down, causing air to move and a faint “clap” to be heard.

Think of it as geomagnetic thunder.

A spectral analysis of the “thunderclap” (above) shows dominant frequencies between 1 kHz and 2 kHz, squarely in the range of human hearing. You have to be quiet to hear them, though.

“People who talk and walk around, concentrating on picture taking, might never hear a single sound related to aurora,” says Laine. “You have to stop all other activities and focus on listening. We Finns are probably good at this because we have received more than 300 reports of sound observations during the Auroral Acoustics Project.”

Over the years, Laine has learned that a geomagnetic storm, by itself, is not enough to produce these thunderclaps. “A strong inversion layer is also required,” he says. “The inversion layer acts like an electrostatic loudspeaker. Without it there are no sounds.” This explains why many geomagnetic storms are silent. The local weather has to be just right — as it was on Oct. 7th.

Realtime Aurora Photo Gallery