Astronomy Archives

September 23, 2013December 23, 2015 by David Dickinson

Comet ISON: A Viewing Guide from Now to Perihelion

Comet ISON, as seen on September 22, 2013 at 10:00 UTC (6:00 am EDT) from Yellow Springs, Ohio, using a QHY8 CCD camera and a home-made 16 inch diameter telescope. 15 minute exposure. Credit and copyright: John Chumack.

Perhaps you’ve read the news. This Fall, the big ticket show is the approach of Comet C/2012 S1 ISON. The passage of this comet into the inner solar system has been the most anticipated apparition of a comet since Hale-Bopp in 1997.

Many backyard observers will get their first good look at Comet ISON in the coming month. If you want to see this comet for yourself, here’s everything you’ll need to know!

A composite image of Comet ISON as seen from the Hubble Space Telescope on April 30th, 2013. (Credit: HubbleSite.org/Go/ISON).

Discovered on September 21^st, 2012 by Artyom-Kislovodsk and Vitaly Nevsky using the International Scientific Optical Network’s (ISON) 0.4 metre reflector, this comet has just passed out from behind the Sun from our Earthly vantage point this summer to once again become visible in the dawn sky.

Of course, there’s much speculation as to whether this will be the “comet of the century” shining as “bright as the Full Moon” near perihelion. We caught up with veteran comet observer John Bortle earlier this year to see what skywatchers might expect from this comet in late 2013. We’ve also chronicled the online wackiness of comets past and present as ISON makes its way into the pantheon as the most recently fashionable scapegoat for “the end of the world of the week…”

But now it’s time to look at the astronomical prospects for observing Comet ISON, and what you can expect leading up to perihelion on November 28^th.

Comet ISON imaged by Efrain Morales on September 22nd. (Credit: Efrain Morales/Jaicoa Observatory, used with permission). — Comet ISON as recently imaged by Efrain Morales on September 22nd. (Credit: Efrain Morales/Jaicoa Observatory, used with permission).

Advanced amateur astronomers are already getting good images of Comet ISON, which currently shines at around +12^th magnitude in the constellation Cancer. And although NASA’s Deep Impact/EPOXI mission is down for the count, plans are afoot for the Curiosity rover and the Mars Reconnaissance Orbiter to attempt imaging the comet when it makes its closest approach to the Red Planet on October 1^st at 0.0724 Astronomical Units (A.U.) or 10,830,000 kilometres distant. If MSL is successful, it would be the first time that a comet has been observed from the surface of another world.

Currently, ISON sits about a magnitude below the projected light curve, (see below) but that isn’t all that unusual for a comet. Already, there’s been increasing talk of “ISON being a dud,” but as Universe Today’s Nancy Atkinson pointed out in a recent post, these assertions are still premature. The big question is what ISON will do leading up to perihelion, and if it will survive its passage 1.1 million kilometres above the surface of the Sun on November 28^th to become a fine comet in the dawn skies in the weeks leading up to Christmas.

ISON is already starting to show a short, spikey tail in amateur images. Tsutomu Seki estimated it to be shining at about magnitude +11.1 on September 16th. Keep in mind, a caveat is in order when talking about the magnitudes of comets. Unlike stars, which are essentially a point source, the brightness of a comet is spread out over a large surface area. Thus, a comet may appear visually fainter than the quoted magnitude, much like a diffuse nebula. Although +6^th magnitude is usually the limit for naked eye visibility, I’ll bet that most folks won’t pick up ISON with the unaided eye from typical suburban sites until it breaks +4^th magnitude or so.

(Credit: NASA CIOC/Matthew Knight. used with permission). — The recent revised light curve projected for Comet ISON (Credit: NASA CIOC/Compiled by Matthew Knight of the Lowell Observatory).

The forward scattering of light also plays a key role in the predicted brightness of a comet. The November issue of Astronomy Magazine has a great article on this phenomenon. It’s interesting to note that ISON stacks up as a “9” on their accumulated point scale, right at the lower threshold of comet “greatness,” versus a 15 for sungrazing Comet C/1965 S1 Ikeya-Seki. Another famous “9” was Comet C/1996 B2 Hyakutake, which passed 0.1018 A.U. or 15.8 million kilometres from Earth on March 25, 1996.

ISON will pass 0.429 A.U. or 64.2 million kilometres from Earth the day after Christmas. Bruce Willis can stay home for this one.

Here is a blow-by-blow breakdown of some key dates to watch for as ISON makes its plunge into the inner solar system:

-September 25^th: ISON crosses the border from the astronomical constellation of Cancer into Leo.

-September 27^th: ISON passes 2 degrees north of the planet Mars.

The path of Comet ISON from October 1st to November 21st. The position of the Sun is shown on the final date. (Created by the Author using Starry Night Education software).

-October 1^st: The 12% illuminated waning crescent Moon passes 10 degrees south of Mars & ISON.

-Early October: ISON may break +10^th magnitude and become visible with binoculars or a small telescope.

-October 4th: New Moon occurs. The Moon then exits the dawn sky, making for two weeks of prime viewing.

–October 10th: ISON enters view of NASA’s STEREO/SECCHI HI-2A CAMERA:

The path of ISON as it enters the view of STEREO. Credit: NASA/ISON Observing campaign)

-October 16^th: ISON passes just 2 degrees NNE of the bright star Regulus, making a great “guidepost” to pin it down with binoculars.

-October 18^th: The Full Moon occurs, after which the Moon enters the morning sky.

-October 26^th: A great photo-op for astro-imagers occurs, as ISON passes within three degrees the Leo galaxy trio of M95, M96, & M105.

The position of Comet ISON on October 26th in Leo. (Created by the author in Stellarium). — The position of Comet ISON on October 26th in Leo near Mars and a trio of galaxies. (Created by the author in Stellarium).

-October 30^th: The 17% illuminated Moon passes 6 degrees south of ISON.

-Early November: Comet ISON may make its naked eye debut for observers based at dark sky sites.

-November 3^rd: A hybrid (annular-total) solar eclipse occurs, spanning the Atlantic and Central Africa. It may just be possible for well placed observers to catch sight of ISON in the daytime during totality, depending on how quickly it brightens up. The Moon reaching New phase also means that the next two weeks will be prime view time for ISON at dawn.

-November 5^th: ISON crosses the border from the astronomical constellation of Leo into Virgo.

-November 7^th: ISON passes less than a degree from the +3.6 magnitude star Zavijava (Beta Virginis).

-November 8^th: ISON passes through the equinoctial point in Virgo around 16:00 EDT/20:00 UT, passing into the southern celestial hemisphere and south of the ecliptic.

-November 14^th: ISON passes less than a degree from the 10^th magnitude galaxy NGC 4697.

-November 17^th: The Moon reaches Full, passing into the morning sky.

-November 18^th: ISON passes just 0.38 degrees north of the bright star Spica.

-November 22^nd: ISON crosses into the astronomical constellation of Libra.

-November 23^rd: ISON sits 4.7 degrees SSW of the planet Mercury and 4.9 SSW of Saturn, respectively.

Looking east before dawn on the morning of November 23rd. (Created by the author using Starry Night Education software). — Looking east before dawn on the morning of November 23rd. Note comet 2P/Encke nearby! (Created by the author using Starry Night Education software).

-November 25^th: ISON pays a visit to another famous comet, passing just 1.2 degrees south of short period comet 2P/Encke which may shine at +8^th magnitude.

-November 27th: ISON enters the field of view of SOHO’s LASCO C3 coronagraph.

-November 28^th: ISON reaches perihelion at ~18:00 PM EST/ 23:00 UT.

After that, all bets are off. The days leading up to perihelion will be tense ones, as ISON then rounds the Sun on a date with astronomical destiny. Will it join the ranks of the great comets of the past? Will it stay intact, or shatter in a spectacular fashion? Watch this space for ISON updates… we’ll be back in late November with our post-perihelion guide!

Be sure to also enjoy recently discovered Comet C/2013 R1 Lovejoy later the year.

Got ISON pics? Send ’em in to Universe Today!

September 19, 2013March 16, 2017 by Fraser Cain

What is a Dyson Sphere?

As long as humans survive, we will likely be increasing our energy consumption. We want better transportation, faster computers, and stuff we just can’t imagine yet.

That’s going to take energy, and lots of it.

If you plot our overall use since the industrial era, you can see it’s a line that just goes up and up. There will come a time in the future when we’ve exhausted all the fossil and nuclear fuels. And once we’ve harvested as much wind, solar and geothermal energy as our planet can produce, we’re going to need to move out into space and collect energy directly from the Sun.

We will construct larger and larger solar arrays, beaming the energy back to Earth. Inevitably, we’ll enclose the entire Sun in a cloud of solar satellites, allowing us to make use of 100% of the radiation it’s emitting.

This is a Dyson sphere.

The concept was developed as part of a research paper in 1960 by the physicist Freeman Dyson. In a thought experiment, he assumed that the power needs for civilizations never stops increasing.

If our descendents could actually figure out how to enclose our star in a rigid shell, we’d have 550 million times more surface area than Earth has right now, and generate 384 yottawatts of energy.

Sounds great, lots of living space and free energy. But there are a host of problems.

There wouldn’t be any gravity to keep anything stuck to the surface of sphere – it would all drop down towards the star and be destroyed. The sphere would be free floating in space, and unless you could keep it balanced in relation to the star, it would eventually collide with it.

Finally, there might not be enough material to build a shell. This advanced civilization would need to make use of all our planets, asteroids and comets. In fact, even if you dismantled everything in the Solar System, you’d only have enough to build a shell about 15 cm-thick.

The physical strength of this material would have to be immense; otherwise the sphere itself would just implode and collapse into the star.

Dyson himself freely admitted that the idea of a rigid shell surrounding a star is unfeasible. Instead, he and others have proposed that civilizations would probably build a dense swarm of objects on independent orbits around their star – a Dyson cloud, or maybe a Dyson ring.

Each solar satellite would be stable on its own, and capable of beaming its energy back to some planet.

Artist's impression of a solar sail. Image credit: NASA — Artist’s impression of a solar sail. Image credit: NASA

You could also build a cloud of solar sails. These objects would be held in perfect balance between the gravity pulling them inward, and the light pressure from the Sun pushing them outward. They wouldn’t need to orbit at all to maintain a static distance from the Sun.

A full Dyson Sphere is probably impossible, but if we assume that alien civilization’s energy needs will continue to grow like ours, it makes sense to search the galaxy for megastructures. Just in case.

Even though the shell would absorb the light and high energy radiation from the star, it would still emit infrared radiation which would be detectable in our telescopes. Even a partial Dyson cloud would give off a telltale light signature as it obscured the light from a star.

This gives us yet another way we could search for extraterrestrial civilizations. And if we did find a full Dyson sphere, out there in the Milky Way. Well, let’s just hope they’re nice aliens.

Update: And as it turns out, we may be closer to finding one that previously thought. Using data obtained by the Kepler probe, a group of planet hunters associated with the Planet Hunters project recently observed light fluctuations coming from KIC 8462852. This F-type main-sequence star, located in the constellation Cygnus, is approximately 1,480 light years (454 parsecs) from Earth.

In their paper, submitted to arXiv, the team offered possible explanations for the light fluctuations, most of which are admittedly problematic. Using high-resolution spectroscopy, spectral energy distribution fitting, and Fourier analyses of the Kepler light curve, they conclude that the most likely scenario is the passage of a family of exocomet fragments.

Another possible explanation that has been ventured is that the light fluctuations could be caused by the presence of mega-structures, which would indicate the presence of sentient extra-terrestrial life. The SETI institute has since conducted radio reconnaissance of KIC 8462852, and their initial findings provided no indications of technology associated with radio signals.

Still, the mere possibility that this could be the first-ever indication of a possible Dyson Sphere in our galaxy is exciting, and has triggered a great deal of speculation and excitement. Stay tuned for more information as it becomes available.

September 19, 2013December 23, 2015 by David Dickinson

More ISON Craziness: Tales of Popes, a Prophet and a Comet

Comet Halley as seen from the Kuiper Airborne Observatory in 1986. (Credit: NASA).

There’s an astronomical tall tale from the Middle Ages that seems to get recycled as factual every time a “great” comet rolls around. This week, we thought we’d look at a story that just won’t die, as well as a new twist in comet conspiracy that’s rolling around ye’ ole ‘Net.

We’ve debunked the current craziness surrounding ISON recently, but apparently our work isn’t finished! Comets seem to bring ‘em out of the woodwork. Today, we’ll discuss how that old prophet of doom Nostradamus may have “predicted” Comet ISON being part of the ‘end times,’ but first, let’s look at an astronomical tale of the past. Did a pope really excommunicate the most famous of all comets?

The mid-15^th century was a trying time for Medieval Europe. The Black Death had decimated the population of Europe a century prior, and the armies of the Ottoman Turks were advancing from the east. A bright comet could only bear ill will in the minds of the superstitious.

Pope Callixtus III: the ecommunicator of comets? (Credit: Museo de la Catherdral de Valencia). — Pope Callixtus III: the excommunicator of comets? (Credit: Museo de la Cathedral de Valencia).

It was into this setting that Pope Callixtus III came into power in 1455. Callixtus was the first of two popes fielded by the Spanish Borgia family, which would later include his nephew Rodrigo who became Pope Alexander the VI, as depicted in the Showtime series The Borgias.

A fine the apparition of Halley’s Comet occurred in June and July 1456. Belgrade was to come under siege by the Ottoman Turks from July 4^th to 22^nd of that year, and the Fall of Constantinople on May 29^th, 1453 to Mehmed II was still fresh on everyone’s mind.

Astronomical signs and omens were a hot topic as well. The partial lunar eclipse of May 22nd, 1453 was seen by many to have fulfilled prophecy that an eclipse would mark the fall of Constantinople. Of course, there are from 4 to 7 eclipses that can be seen on any given year, and lunar eclipses are visible from the entire moonward facing side of the Earth. It’s not too tough to find one to fit any given bill of gloom and doom.

Keep in mind, Halley’s Comet wasn’t even identified in the 15th century as the same comet that was returning once every 75.3 years. That fact wouldn’t be uncovered until Edmund Halley successfully predicted the return of the comet that now bears his name on Christmas Day 1758.

Halley’s Comet would’ve been a spectacular sight in the early summer of 1456, unfurling a tail that was said to have been 60 degrees long and spanning the constellations of Cancer and Leo. The brilliant comet would’ve been a conspicuous object for up to three hours after sunset, and it’s certain that observers around the Mediterranean, including a Rome-based pope would’ve seen it.

A depiction of the passage of Comet Halley through the constellations of Cancer & Leo in 1456. (Wikimedia Commons image in the Public Domain).

But did the pope actually excommunicate the comet to assuage the fears of the European populace of an invasion from the east?

While a quixotic story, the idea that a pope could’ve banned a heavenly body from salvation is apocryphal as best. The Papal Bull issued by Callixtus III on June 29^th, 1456 called for prayers and penance and the ringing of church bells in light of the cruelty visited upon Eastern Europe by invaders from the east, but makes no mention of the comet. In fact, no primary source for the tale exists.

The story seems to have gotten its start with a historian named Platina, who wrote a biography of Callixtus III in 1471. Here we find the appearance of:

“A hairy reddish comet appearing for several days… Callixtus, in order to avert the wrath of God, ordered processions to be held…”

No out right excommunication per se, but the Pope and the comet were now forever linked in the eye of history.

The pitched Battle of Nandorfehervar during the 1456 Siege of Belgrade. (Wikimedia Commons scan in the Public Domain). — The pitched Battle of Nandorfehervar during the 1456 Siege of Belgrade. (Painting by Rubens in the Public Domain).

French mathematician and astronomer Pierre-Simon Laplace later gave the excommunication tale a boost in the late 18^th century, and further embellishment followed from astronomer François Arago writing in 1832.

Keep in mind, these are historical works written down some years after the fact, often translated from Latin to French to English—ideas such as LaPlace’s “conjurer la comete” can easily come across as to “exorcise” or “excommunicate” a comet. Also, political satire of popes, both alive and dead, was common after the start of the Protestant Reformation. Halley’s Comet also made a fine apparition in 1835, and Arago may have been looking for something to captivate the public with in anticipation.

But although this story was debunked over a century ago, it still makes its rounds. None other than Carl Sagan repeated the excommunication story in his book Comet (sorry Carl!) although he also notes that the tale is apocryphal. Although the story of the excommunication of Halley’s Comet has been debunked time and again, a search of the Internet reveals about an even split between the credulous and the skeptical.

But there is also a current mythos being born around Comet ISON, Pope Francis and Nostradamus on ye ole web. For the most part, it has to do with — you guessed it — the end of the world. As per the usual, great comets are harbingers of catastrophic events. Combine the words of Nostradamus with the fact that 2013 has been hyped as “The Year of the Comet,” along with Pope Benedict’s unusual resignation, and that equals The End of Time.

If you don’t believe me, search of Comet/ISON/Pope and see what turns up. The gist of the prophecy cites a quatrain stating that:

“the great star for seven days shall burn

So nakedly clear like two suns appearing

The large dog all night howling

While the great Pontiff shall change his territory.”

Of course, the quatrains of Nostradamus, like all prophecies, are suitably vague enough that they could be interpreted almost in whatever fashion suits the reader. And again, we’re looking at the old 16^th century French translated into modern English.

And like eclipses, there are a handful of comets every year. Most reach binocular visibility, and a few may go on to become visible to the naked eye. We’ve already had two comets that crossed this threshold this year, comet C/2011 L4 PanSTARRS and C/2012 F6 Lemmon.

Comet ISON as seen from the Hubble Space Telescope- no popes were harmed in the taking of this image! (credit: NASA/ESA/STScI/AURA). — Comet ISON as seen from the Hubble Space Telescope… no popes were harmed or forced to flee in the taking of this image. (credit: NASA/ESA/STScI/AURA).

And Comet ISON’s “greatness” is still very much in question. Its currently only at 12^th magnitude and probably won’t be a naked eye object until at least early November. And it certainly won’t have the appearance of a second Sun!

I’ll leave it to the armchair predictors of comet doom to decipher what “the large dog howling” even means. The chief logical fallacy evoked by the adherents of Nostradamus is what is known as retrofitting— it’s easy to take a cryptically predicted disaster and find an earthquake, eclipse, and yes, even a comet that falls roughly near the given date.

Of course, if ISON kicks into high gear, then we could really be in for a grand show, along with an accompanying upswing in comet hysteria. And thus, the tireless vigilance against comet-mania continues. Hey, we’re all after “link juice” and the almighty SEO, right? Of course, the real harm comes when something like the 1997 Heaven’s Gate mass suicide, inspired by rumors of an alien spacecraft following comet Hale-Bopp occurs.

Halleys March 9 2062 — Halley’s Comet as seen on the morning of March 9th, 2062. (Created by the author using Starry Night Education software).

In short, enjoy the show as ISON approaches, read the online tales of popes and comets past… but as rapper and surreptitious promoter of skepticism Chuck D of Public Enemy implores us, don’t believe the hype.

Maybe we’ll finally be an enlightened and rational species when Halley’s Comet pays us a visit again starting in the summer of 2061 through the spring of 2062!

-For an exhaustive look at the myth of the excommunication of Halley’s Comet, Read An Historical Examination of the Connection of Callixtus III with Halley’s Comet published in 1910.

-To see a (mostly) woo free version of the current Comet ISON versus Pope Francis mythos, (with quatrains) check out this article from news.com.au. Hey, we sift through woo so you don’t have to!

September 18, 2013December 23, 2015 by Shannon Hall

New Molecules Detected in Io’s Atmosphere

An image of Io taken by the automated spacecraft: Galileo. Image Credit: NASA

Io – Jupiter’s innermost Galilean moon – is the most geologically active body in the Solar System. With over 400 active volcanic regions, plumes of sulfur can climb as high as 300 miles above the surface. It is dotted with more than 100 mountains, some of which are taller than Mount Everest. In between the volcanoes and mountains there are extensive lava flows and floodplains of liquid rock.

Intense volcanic activity leads to a thin atmosphere consisting mainly of sulfur dioxide (SO₂), with minor species including sulfur monoxide (SO), sodium chloride (NaCl), and atomic sulfur and oxygen. Despite Io’s close proximity to the Earth the composition of its atmosphere remains poorly constrained. Models predict a variety of other molecules that should be present but have not been observed yet.

Recently a team of astronomers from institutions across the United States, France, and Sweden, set out to better constrain Io’s atmosphere. They detected the second-most abundant isotope of sulfur (34-S) and tentatively detected potassium chloride (KCl). The latter is produced in volcanic plumes – suggesting that these plumes continuously contribute to Io’s atmosphere.

Expected yet undetected molecular species include potassium chloride (KCl), silicone monoxide (SiO), disulfur monoxide (S₂O), and various isotopes of sulfur. Most of these elements emit in radio wavelengths.

“Depending on their geometry, some molecules emit at well known frequencies when they change rotational state,” Dr. Arielle Moullet, lead author on the study, told Universe Today. “These spectral features are called rotational lines and show up in the (sub)millimeter spectral range.”

These observations were therefore obtained at the Atacama Pathfinder Experiment (APEX) antenna – a radio telescope located 16,700 feet above sea level in northern Chile. The main dish has a diameter of 12 meters, and is a prototype antenna for the Atacama Large Millimeter Array (ALMA).

The Atacama Pathfinder (APEX) antenna. Image Credit: ESO

Following 16.5 hours of total observation time and months of data reduction and analysis, Moullet et al. made a tentative detection of potassium chloride (KCl). Io’s volcanic ejecta produce a large plasma torus around Jupiter, which inlcudes many molecular species including potassium. This detection is therefore considered the “missing link” between Io and this plasma torus.

The team also made the first detection of one of Sulfur’s isotopes known as 34-S. Sulfur has 25 known isotopes – variants of sulfur that still have 16 protons but differ in their number of neutrons. 34-S is the second most abundant isotope with 18 neutrons.

Previously, the first-most abundant isotope of sulfur, 32-S with 16 neutrons, had been detected. Surprisingly the ratio between the two (34/32 S) is twice as high as the solar system reference, suggesting that there is an abundance of 34-S. A fraction this high has only been reported before in a distant quasar – an early galaxy consisting of an intensely luminous core powered by a huge black hole.

“This result tells us that there probably is some fractionation process that we haven’t yet identified, which is happening either in the magma, at the surface, or in the atmosphere itself,” explains Dr. Moullet. Something somewhere is producing an unexplained abundance of this isotope.

Other expected yet undetected molecules including silicone monoxide and disulfur monoxide remain undetected. It is possible that these molecules are simply not present, but more likely that the observations are not sensitive enough to detect them.

“To perform a deeper spectral search with a better sensitivity, our group has been awarded observation time with the Atacama Large Millimeter Array, a cutting edge interferometric facility in Chile, which will eventually include more than fifty 12-meter wide dishes,” explains Dr. Moullet. “We are in the process of analyzing our first dataset obtained with sixteen antennas, which is already much more sensitive than the APEX data.”

While Io is certainly an extreme example, it will likely help us characterize volcanism in general – providing a better understanding of volcanism here on Earth as well as outside the Solar System.

The paper has been accepted for publication in The Astrophysical Journal and is available for download here.

September 18, 2013December 23, 2015 by Bob King

Tonight’s Harvest Moon Is For The Birds … Really!

The moon provides the perfect backdrop for watching birds migrate at night. Observers with spotting scopes and small telescopes can watch the show anytime the moon is at or near full. Photo illustration: Bob King

Tonight’s the Harvest Moon, the full Moon closest to the fall equinox. A perfect time to catch a big orange Moon on the horizon AND the annual fall bird migration. Every September and October anyone with a small telescope or spotting scope magnifying 30x can enjoy the sight of one bird after another flying over the cratered lunar landscape. It’s so easy.

Point your telescope at the Moon and watch for dark silhouettes to flutter across its face. Because the angle of the full Moon’s path to the horizon is very shallow in September and October, the time difference between successive moonrises is only about 20-30 minutes instead of the usual 50-60. That means you’ll catch both moonlight and bird flight on successive nights without having to stay up late.

The Harvest Moon rises over Lake Superior in Duluth, Minn. When you’re out enjoying this year’s full moon on Wednesday and Thursday nights, watch for the dark band you see in the photo. That’s the Earth’s shadow. It’s visible for about 15-20 after sunset and topped by the pink-tinged Belt of Venus, where the atmosphere is still reflecting reddened sunlight. Credit: Bob King — The Harvest Moon rises over Lake Superior in Duluth, Minn last September. When you’re out moon and birdwatching, look for the dark band below the rising moon. That’s the Earth’s shadow. It’s visible for about 15-20 after sunset and topped by the pink-tinged “Belt of Venus”, where the atmosphere is still reflecting reddened sunlight. Credit: Bob King

Many birds migrate at night both because it’s cooler and to avoid predators that could otherwise pick them off in a daylight run. Identifying the many warblers, blackbirds, sparrows, vireos, orioles and other species that fly across the moon while we sleep may be next to impossible for anyone but an expert, but seeing them is easy. Two night ago for fun, I counted a dozen birds in the five-minute interval around 10 o’clock through my 10-inch telescope at low power (76x). Assuming they continued to fly by at a steady rate, I could potentially have spotted 144 birds in just an hour’s time.

*Two of my favorite migrating birds: the winter wren (left) and chestnut-sided warbler. Credit: Bob King*

As you might suspect, most of those birds crossed the Moon from north to south (about two-thirds) with the other third traveling either east to west or northeast to southwest. Only one little silhouette flapped back up north in the ‘wrong’ direction.

According to the Chipper Woods Bird Observatory, located in Indianapolis, most nighttime migrators begin their flight right after sunset and continue until about 2 a.m. Peak time is between 11 p.m. and 1 a.m. Bird typically migrate at altitudes ranging from 1,500 to 5,000 feet, but on some nights, altitudes may range from 6,000 and 9,000 feet. I could tell the high ones from the low ones by their size and sharpness. Nearby birds flew by out of focus, while distant ones were sharply defined and took longer to cross the moon.

Check out this animated wave of bird migration after sunset on Aug. 27, 2013 made with NEXRAD. Birds are visible funneling down both shores of Lake Superior and moving south of Duluth, Minn (city at center). Credit: NWS — Check out this animation showing a wave of bird migration after sunset on Aug. 27 made with NEXRAD. Birds are visible funneling down both shores of Lake Superior and moving south of Duluth, Minn (city at center). Credit: NWS

While birders may continue to use the moon night birding, they now have a new tool – NEXRAD or NEXt-generation of Weather RADar. About 150 NEXRAD sites were set up in the 1990s to track weather and storm systems across the U.S. When precipitation gets pinged by the radar’s pulse it reflects back a signal that identifies it as rain, snow or whatever. Included in the information is the material’s speed and direction of travel. NEXRAD works equally well on meteorite falls, birds and even insects. While storm activity typically shows up as familiar blotches of yellow, orange and red, birds appear as fine stipplings. By compiling NEXRAD loops, during particularly heavy migration times, you can actually watch swarms of birds wing their way south. Click HERE for a map of all U.S. NEXRAD locations, each of which links to current radar maps.

On the less technological side, watching birds pass across the Moon in a small telescope is a very pleasant activity reminiscent of meteor shower watching. At first you see nothing, then blip! a bird (meteor) flies by. You wait another minute and then suddenly two more appear in tandem. Both activities give you that delicious sense of anticipation of what the next moment might hold.

The best time to watch the nighttime avian exodus is around full Moon, when the big, round disk offers an ideal spotlight on the birds’ behavior, but anytime between waxing and waning gibbous phase will work. It’s an enchanting sight to see Earth’s creatures streak across an alien landscape, and another instance of how a distant celestial body “touches” Earth in unexpected ways.

September 17, 2013March 16, 2017 by Fraser Cain

Is There Really a Planet X?

Have you heard there’s a giant planet in the Solar System headed straight towards Earth?

At some point in the next few months or years, this thing is going to crash into Earth or flip our poles, or push us out of our orbit, or some other horrible civilization destroying disaster.

Are these rumours true?

Is there a Planet X on a collision course with Earth?

Unlike some of the answers science gives us, where we need to give a vague and nuanced answers, like yes AND no, or Maybe, well, it depends…

I’m glad to give a straight answer: No.

Any large object moving towards the inner Solar System would be one of the brightest objects in the night sky. It would mess up the orbits of the other planets and asteroids that astronomers carefully observe every night.

There are millions of amateur astronomers taking high quality images of the night sky. If something was out there, they’d see it.

These rumours have been popping up on the internet for more than a decade now, and I’m sure we’ll still be debunking them decades from now.

What people are calling Planet X, or Nibiru, or Wormwood, or whatever doesn’t exist. But is it possible that there are large, undiscovered objects out in the furthest reaches of Solar System?

Sure.

Astronomers have been searching for Planet X for more than a hundred years. In the 1840s, the French mathematician Urbain Le Verrier calculated that another large planet must be perturbing the orbit of Uranus. He predicted the location where this planet would be, and then German astronomer Johann Gottfried Galle used those coordinates to discover Neptune right where Le Verrier predicted.

The famed astronomer Percival Lowell died searching for the next planet in the Solar System, but he made a few calculations about where it might be found.

A young Clyde Tombaugh with one of his famous homemade telescopes. (Credit : NASA/GSFC).

And in 1930, Clyde William Tombaugh successfully discovered Pluto in one of the locations predicted by Lowell.

Astronomers continued searching for additional large objects, but it wasn’t until 2005 that another object the size of Pluto was finally discovered by Mike Brown and his team from Caltech: Eris. Brown and his team also turned up several other large icy objects in the Kuiper Belt; many of which have been designated dwarf planets.

We haven’t discovered any other large objects yet, but there might be clues that they’re out there.

In 2012, the Brazilian astronomer Rodney Gomes calculated the orbits of objects in the Kuiper Belt and found irregularities in the orbits of 6 objects. This suggests that a larger object is further out, tugging at their orbits. It could be a Mars-sized object 8.5 billion km away, or a Neptune-sized object 225 billion km away.

A false-color, visible-light image of Comet ISON taken with Hubble's Wide Field Camera 3. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) — A false-color, visible-light image of Comet ISON taken with Hubble’s Wide Field Camera 3. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

There’s another region at the edge of the Solar System called the Oort Cloud. This is the source of the long-period comets that occasionally visit the inner Solar System. It’s possible that large planets are perturbing the orbits of comets with their gravity, nudging these comets in our direction.

So, feel free to ignore every single scary video and website that says an encounter with Planet X is coming.

And use that time you saved from worrying, and use it to appreciate the amazing discoveries being made in space and astronomy every day.

September 17, 2013December 23, 2015 by Shannon Hall

Planet Evaporates Due to Stellar Flare

An artist's conception of a disintegrating planet - creating a trail of dust - around its rocky star.

Solar flares – huge eruptions of charged particles from the Sun – present little threat to Earth. On a few rare occasions these particles may disrupt our communications systems and cause radio blackouts. But they tend to be more aesthetically pleasing than harmful. It’s certainly a sight to be seen as these energetic particles collide with our atmosphere, resulting in a cascade of colorful lights – the aurora borealis.

Fortunately our planet provides the protection necessary from such harmful space radiation. But not all planets are quite so lucky. Take for instance Kepler’s latest object of interest: KIC 12557548b, a super Mercury-size planet candidate. Astronomers have recently found that due to this star’s activity – producing massive stellar flares – the planet itself is evaporating.

Only last year, four different sources published evidence that this rocky planet was disintegrating. Thanks to Kepler, it quickly became clear that the total amount of light from KIC 12557548 as a function of time – the light curve of the system – dropped every 15.7 hours as a planet orbited it. But the amount of light blocked due to the transiting planet varied from 0.2% to more than 1.2%.

The amount of light blocked is dependent on the size of the planet. A Jupiter-size planet will block more light than a Mercury-size planet. The variations here suggest a range for the size of the planet: from a super Mercury-sized planet to a Jupiter-sized planet.

But this wasn’t the planet’s only enigma. It also has an asymmetric light curve. The total light from the star drops steadily as the planet begins its transit, plateaus as the planet fully covers the disk of the star, and then increases as the planet ends its transit. But the rate at which the light drops is much faster than the rate at which it increases. It takes longer for the light curve to return to its original brightness, hinting at a tail of debris that trails the planet, continuing to block light.

Blah — The light curves of KIC 12557548b. The left-hand plot represents deep transits, whereas the right-hand plot represents more shallow transits. Both plots show a clear asymmetry. Source: Brogi et al. 2012

It appears that the planet is evaporating – emitting small particles of dust into orbit, which then trails behind it. The varying transit depth reflects the amount of dust currently evaporating.

Recently a team from the University of Tokyo analyzed the system in more detail, attempting to explain why this tiny planet is evaporating. “We found that the transit depth negatively correlates with the modulation of the stellar flux,” Dr. Kawahara, lead author on the study, told Universe Today. “The dust amount increases when the planet is located in front of the star spots.”

The transit depth does not vary randomly, but every 22.83 days. This coincides with the modulation of the stellar flux, or simply the stellar rotation period. Star spots may be indirectly detected by a star’s noticeable decrease in stellar flux. Because these star spots are large (much larger than sunspots) they last for long periods of time, and may be used to deduce the star’s rotation period.

Kawahara et al. found that the transit depth periodically varies with the stellar rotation rate – finding a correlation between stellar activity and the rate at which the planet is evaporating.

“Energy from the star spots increases the amount of dust and atmosphere from the planet,” explains Dr. Kawahara. The extreme heat and wind is enough to speed up the motions of the dust molecules; making them fast enough to escape the planet’s gravitational pull.

Future spectroscopic studies may search for molecules in the evaporating atmosphere of KIC 12557548b. But Dr. Kawahara remarks that due to the planet’s faintness it is unlikely. His best hope is that future studies may instead find a similar object closer to us, that may be more easy to study.

The finding is published in The Astrophysical Journal Letters and is available for download here.

September 16, 2013December 23, 2015 by Tammy Plotner

Endings and Beginnings – Magnetic Jets Shape Stellar Transformation

A jet of energetic particles (shown in magenta) is shaping the environment around the star IRAS 15445-5449. Infrared light from dusty material which the jet has already shaped into a symmetric form is shown in green. The star itself is hidden by dust in its environment. Credit: E. Lagadec/ESO/A. Pérez Sánchez)

The incredible visual appearance of planetary nebulae are some of the most studied and observed of deep space objects. However, these enigmatic clouds of gas have defied explanation as to their shapes and astronomers are seeking answers. Thanks to a new discovery made by an international team of scientists from Sweden, Germany and Austria, we have now observed a jet of high-energy particles in the process of being ejected from an expiring star.

When a sun-like star reaches the end of its life, it begins to shed itself of its outer layers. These layers blossom into space at speeds of a few kilometers per second, forming a variety of shapes and sizes – yet we know little about what causes their ultimate appearance. Now astronomers are taking a close look at a rather normal star that has reached the end of its life and is beginning to form a planetary nebula. Cataloged as IRAS 15445-5449, this stellar study resides 230,000 light years away in the constellation of Triangulum Australe (the Southern Triangle). Through the use of the CSIRO Australia Telescope Compact Array, a compliment of six 22-meter radio telescopes in New South Wales, Australia, researchers have found what may be the answer to this mystery… high-speed magnetic jets.

“In our data we found the clear signature of a narrow and extremely energetic jet of a type which has never been seen before in an old, Sun-like star,” says Andrés Pérez Sánchez, graduate student in astronomy at Bonn University, who led the study.

How does a radio telescope aid researchers in an optical study? In this case the radio waves emitted by the dying star are compatible with the trademark high-energy particles they are expected to produce. These “spouts” of particles travel at nearly the speed of light and coincident jets are also known to emanate from other astronomical objects that range from newborn stars to supermassive black holes.

“What we’re seeing is a powerful jet of particles spiraling through a strong magnetic field,” says Wouter Vlemmings, astronomer at Onsala Space Observatory, Chalmers. “Its brightness indicates that it’s in the process of creating a symmetric nebula around the star.”

Will these high-energy particles contained within the jet eventually craft the planetary nebula into an ethereal beauty? According to the astronomers, the current state of IRAS 15445-5449 is probably a short-lived phenomenon and nothing more than an intense and dramatic phase in its life… One we’re lucky to have observed.

“The radio signal from the jet varies in a way that means that it may only last a few decades. Over the course of just a few hundred years the jet can determine how the nebula will look when it finally gets lit up by the star,” says team member Jessica Chapman, astronomer at CSIRO in Sydney, Australia.

Will our Sun also follow suit? Right now the answer is unclear. There may be more to this radio picture than meets the ear. However, rest assured that this new information is being heard and might well become the target of additional radio studies. Considering the life of a planetary nebula is generally expected to last few tens of thousands of years, this is a unique opportunity for astronomers to observe what might be a transient occurrence.

“The star may have an unseen companion – another star or large planet — that helps create the jet. With the help of other front-line radio telescopes, like ALMA, and future facilities like the Square Kilometre Array (SKA), we’ll be able to find out just which stars create jets like this one, and how they do it,” says Andrés Pérez Sánchez.

Original Story Source: Royal Astronomical Society News Release.

September 16, 2013December 23, 2015 by David Dickinson

The September Equinox: ‘Tis the Season to Spy the Zodiacal Light

The zodiacal light in the Nevada dawn. The plane of the ecliptic can be traced by Jupiter in Gemini & Mars in the Beehive cluster just below center. (Credit: Cory Schmitz, used with permission).

This week leading up to the September equinox offers you a fine chance to catch an elusive phenomenon in the pre-dawn sky.

We’re talking about the zodiacal light, the ghostly pyramid-shaped luminescence that heralds the approach of dawn. Zodiacal light can also be seen in the post-dusk sky, extending from the western horizon along the ecliptic.

September is a great time for northern hemisphere observers to try and sight this glow in the early dawn. This is because the ecliptic is currently at a high and favorable angle, pitching the zodiacal band out of the atmospheric murk low to the horizon. For southern hemisphere observers, September provides the best time to hunt for the zodiacal light after dusk. In March, the situation is reversed, with dusk being the best for northern hemisphere observers and dawn providing the best opportunity to catch this elusive phenomenon for southern observers.

The clash of the zodiacal light and the plane of our galaxy. (Credit: Cory Schmitz, used with permission).

Cory Schmitz’s recent outstanding photos taken from the Nevada desert brought to mind just how ephemeral a glimpse of the zodiacal light can be. The glow was a frequent sight for us from dark sky sites just outside of Tucson, Arizona—but a rarity now that we reside on the light-polluted east coast of the U.S.

In order to see the zodiacal light, you’ll need to start watching before astronomical twilight—the start of which is defined as when the rising Sun reaches 18 degrees below the local horizon—and observe from as dark a site as possible under a moonless sky.

The Bortle dark sky scale lists the zodiacal light as glimpse-able under Class 4 suburban-to-rural transition skies. Under a Class 3 rural sky, the zodiacal light may extend up to 60 degrees above the horizon, and under truly dark—and these days, almost mythical—Class 1 and 2 skies, the true nature of the zodiacal band extending across the ecliptic can become apparent. The appearance and extent of the zodiacal light makes a great gauge of the sky conditions at that favorite secret dark sky site.

The source of the zodiacal light is tiny dust particles about 10 to 300 micrometres in size scattered across the plane of the solar system. The source of the material has long been debated, with the usual suspects cited as micrometeoroid collisions and cometary dust. A 2010 paper by Peter Jenniskens and David Nesvorny in the Astrophysical Journal cites the fragmentation of Jupiter-class comets. Their model satisfactorily explains the source of about 85% of the material. Dust in the zodiacal cloud must be periodically replenished, as the material is slowly spiraling inward via what is known as the Poynting-Robertson effect. None other than Brian May of the rock group Queen wrote his PhD thesis on Radial Velocities in the Zodiacal Dust Cloud.

But even if you can’t see the zodiacal light, you still just might be able to catch it. Photographing the zodiacal light is similar to catching the band of the Milky Way. In fact, you can see the two crossing paths in Cory’s images, as the bright winter lanes of the Orion Spur are visible piercing the constellation of the same name. Cory used a 14mm lens at f/3.2 for the darker image with a 20 second exposure at ISO 6400 and a 24mm lens at f/2.8 with a 15 second exposure at ISO 3200 for the brighter shot.

The orientation of the ecliptic & the zodiacal band as seen from latitude 30 deg north in September, about 1 hour before sunrise. (Created by the author in Stellarium).

Under a truly dark site, the zodiacal light can compete with the Milky Way in brightness. The early Arab astronomers referred to it as the false dawn. In recent times, we’ve heard tales of urbanites mistaking the Milky Way for the glow of a fire on the horizon during blackouts, and we wouldn’t be surprised if the zodiacal light could evoke the same. We’ve often heard our friends who’ve deployed to Afghanistan remark how truly dark the skies are there, as military bases must often operate with night vision goggles in total darkness to avoid drawing sniper fire.

Another even tougher but related phenomenon to spot is known as the gegenschein. This counter glow sits at the anti-sunward point where said particles are approaching 100% illumination. This time of year, this point lies off in the constellation Pisces, well away from the star-cluttered galactic plane. OK, we’ve never seen it, either. A quick search of the web reveals more blurry pics of guys in ape suits purporting to be Bigfoot than good pictures of the gegenschein. Spotting this elusive glow is the hallmark of truly dark skies. The anti-sunward point and the gegenschein rides highest near local midnight.

And speaking of which, the September equinox occurs this weekend on the 22^nd at 4:44 PM EDT/20:44 Universal Time. This marks the beginning of Fall for the northern hemisphere and the start of summer for the southern.

The Full Harvest Moon also occurs later this week, being the closest Full Moon to the equinox occurring on September 19^th at 7:13AM EDT/11:13 UT. Said Moon will rise only ~30 minutes apart on successive evenings for mid-northern latitude observers, owing to the shallow angle of the ecliptic. Unfortunately, the Moon will then move into the morning sky, drowning out those attempts to spy the zodiacal light until late September.

Be sure to get out there on these coming mornings and check out the zodiacal light, and send in those pics in to Universe Today!

September 16, 2013April 26, 2016 by Elizabeth Howell

Ice Volcanoes Likely Alter Titan’s Surface Brightness: Study

Titan peeks from behind two of Saturn's rings. Another small moon Epimetheus, appears just above the rings. Credit: NASA/JPL/Space Science Institute

Icy volcanoes are likely responsible for changes in brightness on the surface of Titan, the largest moon of Saturn, according to a new study.

Images with the Cassini spacecraft’s visual and infrared mapping spectrometer revealed the brightness, or albedo, of two equatorial areas changing during the study period. Tui Regio (which got darker from 2005 to 2009) and Sotra Patera (which got brighter from 2005 to 2006).

The researchers also pointed to “volcanic-like features” in these areas as evidence that the potential cryovolcanoes, as these icy volcanoes are known, might be connected to an ocean on Titan.

Top: Sotra Patera, a cryovolcanic candidate on Titan that has a one-kilometer crater. (Credit: NASA/JPL Caltech/USGS/University of Arizona). Bottom: The Kirishima volcano in Japan, a terrestrial analogue (Credit: USGS).

“All of these features, plus a need for a methane reservoir and volcanic activity to replenish the methane in the atmosphere, is compatible with the theory of active cryovolcanism on Titan,” stated Anezina Solomonidou , a planetary geologist with the Paris Observatory as well as the National and Kapodistrian University of Athens.

“These results have important implications for Titan’s potential to support life, as these cryovolcanic areas might contain environments that could harbor conditions favorable for life,” Solomonidou added.

Of note, Titan also has a fresh-looking surface with few craters on it, indicating that something might be altering the surface. “Its landscape is remarkably Earth-like with dunes and lakes, erosion due to weathering and tectonic-like features,” a statement on the research added.

There’s been chatter about cryovolcanoes on Titan before. In 2010, researchers said a chain of peaks found on the moon could be evidence of this type of feature. However, a 2012 preliminary California Institute of Technology weather model of the moon explained many of its features without necessarily needing to rely on cryovolcanoes.

Source: European Planetary Science Congress