David Dickinson, Author at Universe Today

October 18, 2016 by David Dickinson

Photobomb: The Moon Occults Aldebaran Wednesday

An occultation of Aldebaran by the Moon: before and after. Image credit and copyright: Eliot Herman.

How about that Hunter’s Supermoon this past weekend, huh? Follow that Moon, as it’s meeting up with the Hyades again this week, and occults (passes in front of) Aldebaran Tuesday night into Wednesday morning.

Here’s the lowdown on the event:

The 86% illuminated waning gibbous Moon occults the +0.9 magnitude star Aldebaran across North America, the Northern Atlantic and Europe. The Moon is three days past Full during the event. Both are located 136 degrees west of the Sun at the time of the event. The central time of conjunction is ~6:40 Universal Time (UT). The event occurs during the daylight hours over western Europe and northwestern Africa and under darkness for southeastern North America, including the eastern United States and Mexico. The Moon will next occult Aldebaran on November 15^th, 2016. This is occultation 24 in the current series of 49 running from January 29^th, 2015 to September 3^rd 2018.

The occultation of Aldebaran by the Moon as seen from London on December 23rd, 2015. Image credit and copyright: Roger Hutchinson.

The graze line is of particular interest during this event. We’re talking about the very edge of the footprint of the Moon’s ‘shadow’ cast by Aldebaran, running through Canada and bisecting the United States. Observers based along this line could see a spectacular ‘grazing occultation’ of Aldebaran by the Moon. We usually think of the limb of the Moon as a smooth curve, but it’s actually jagged. What you may see is Aldebaran wink in and out as light shines down those lunar valleys and is alternately blocked out behind peaks and crater rims. This is an unforgettable sight, and makes for great video. A record of a grazing occultation by multiple observers can also be used to create a profile of the lunar limb. That light from Aldebaran took 65 years to get here, only to be blocked by our Moon at the very last second.

The occultation footpring for tonight's event. The solid lines denote where the occultation occurs under dark night time skies, while the blue lines denote twilight and the broken lines describe where the event occurs in the daytime. Image credit: Occult 4.2. — The occultation footprint for tonight’s event. The solid lines denote where the occultation occurs under dark nighttime skies, while the blue lines denote twilight, and the broken lines describe where the event occurs in the daytime. Image credit: Occult 4.2.

And observers (myself one of them) based in Europe shouldn’t count themselves out. Like brighter planets, you can spy a +1 magnitude star such as Aldebaran near the daytime Moon using binoculars or a telescope… if, of course, you have a high contrast deep blue sky and know exactly where to look for it. The International Occultation Timing Association has a page for the event with a complete list of ingress and egress times for key cities on three continents in the path. We’ll be watching the Wednesday event – clear skies willing — from our present basecamp in the Andalusian foothills just outside of Jimena de la Frontera, Spain.

The northern graze line for tonight's occultation. Note that several major cities lie along the crucial path. Image credit: Dave Dickinson. — The northern graze line for tonight’s occultation. Note that several major cities lie along the crucial path. Image credit: Dave Dickinson.

During our current epoch, the Moon can only occult four +1^st magnitude stars: Regulus, Spica, Antares and Aldebaran. The slow motion movement of the Moon, the Earth and the background stars make this prestigious A-list change over time: until about two millennia ago, you could also count the bright star Pollux in Gemini among them.

In the current century, (2001-2100 AD) the Moon occults Aldebaran 247 times, topped only by Antares (386 times) and barely beating out Spica (220 times).

Timing an occultation is fun and as easy as shooting video of the Moon through a telescope at the appointed time of ingress or egress. Practice on framing the dazzling Moon first well in advance — probably the toughest part is getting the exposure of the bright limb stopped down enough to still see and image the star. We find that shooting anywhere from 1/100^th to 1/500^th frame rate for a gibbous Moon is about right. Don’t be afraid to crank up the magnification a bit, so you can place the bulk of the Moon out of view. Also, catching occultations of stars and planets during waning Moon phases are more challenging than waxing, as the star will ingress behind the bright leading limb and later reappear behind the dark trailing limb (waxing is vice versa).

Observing: Running an audible time hack in the background such as WWV radio out of Fort Collins, Colorado can provide a precise record of the occultation.

But wait, there’s more. When the Moon occults Aldebaran, its also crossing the background V-shaped open star cluster known as the Hyades. Worldwide the waning gibbous Moon also occults Gamma, 51, and Theta^1 and Theta^2, SAO 93975, and 119 Tauri. Chances are, there’s an occultation for YOU to catch this week, regardless of your location.

Want more? Well, the Moon continues to occult Aldebaran every lunation through 2017, and will also start a cycle of passes in front of Regulus on December 18^th. In fact, the next occultation of Aldebaran on November 15th favors central Asia, and the event two lunations from now on December 13^th brings the path back around the North America.

A great close out for 2016, for sure. Don’t miss this week’s occultation!

October 13, 2016 by David Dickinson

This Weekend: A Hunter’s Full Moon Kicks Off Supermoon Season

The #MemoriesInDNA project intends to create an archive of human knowledge which will be sent to the Moon. Credit and copyright: John Brimacombe.

Ready for some lunar action of proxigean proportions? This weekend’s Full Moon ushers in that most (infamous?) of internet ready cultural memes: that of the Supermoon. This moniker stands above the Blood, Mini, and Full Moons both Black and Blue as the Full Moon of the year that folks can’t seem to get enough of, and astronomers love to hate.

But wait a minute: is this weekend’s Full Moon really the closest of the year?

Nope, though it’s close. But this month’s Full Moon does, however, usher in what we like to call Supermoon season.

Let us explain.

First, we’ll let you in on the Supermoon’s not so secret history. Yes, the meme arose over the last few decades, mostly due to the dastardly deeds of astrologers. Y’know, that well meaning friend/coworker/relative/anonymous person on Twitter that constantly mistakes your passion for the night sky as ‘astrology.’ Anyhow, the idea of the Supermoon has gained new life via the internet, and loosely translates as the closest Full Moon of the year. Sometimes, its dressed up with the slightly science-y sounding ‘a Full Moon along the closest 90% of its orbit’ (!) definition.

Now, to know the orbit of the Moon is to understand celestial mechanics. The Moon’s orbit is indeed elliptical, ranging from an average perigee (its closest point to the Earth) of 362,600 kilometers, to an apogee of 405,400 kilometers distant.

Fun fact: the time it takes the Moon to go from one perigee to the next (27.55 days) is one anomalistic month, a fine pedantic point to bring up to said relative/coworker the next time they refer to you as an astrologer.

And yes, the perigee Full Moon is a thing. We even like to throw about the quixotic term of the proxigean Moon, a time when tidal variations are at an extreme. Plus, all perigees are not created equal, but range from 356,400 kilometers to 370,400 kilometers distant, as the Earth-Moon system not only swings around its common barycenter, but the Sun also drags the entire orbit of the Moon around the Earth, completing one complete revolution every 8.85 years in what’s known as the precession of the line of apsides. Note that the nodes of the Moon’s orbit actually move in the opposite direction, with an 18.6 year period.

The complex motion of the Moon. Image credit: Wikimedia Commons/Geologician/Homunculus2.

Yup, the motion of the Moon has given humanity a fine study in Celestial Mechanics 101. Anyhow, we contend that a more succinct definition for a perigee ‘Supermoon’ is simply a Full Moon that falls within 24 hours of perigee. Under this definition, the Full Moon this Sunday on October 16^th occurring at 4:23 Universal Time (UT) certainly meets the criterion, occurring 19 hours and 24 minutes before perigee… as does the Full Moon of November 14^th (2.4 hours from perigee) and December 13^th (just under 24 hours from perigee).

For extra fun, said November 14^th perigee Full Moon is the closest in 30 years; expect Supermoon lunacy to ensue.

A fun place to play with Full and New Moons vs perigee and apogee past present and future is Fourmilab’s Lunar Apogee and Perigee Calculator. Hey, it’s what we do for fun. Looking over these cycles, you’ll notice a pattern of ‘supermoon seasons’ emerge, which moves forward along the calendar about a lunation a year. (that’s our friend the precession of the line of apsides at work again).

(another fun fact: the time it takes for the Moon to return to a similar phase—for example, Full back to Full—is 29.5 days, and known as a synodic month.)

The Full Moon does appear slightly larger at perigee than apogee, to the tune of 29.3′ versus 34.1′ across. This change is enough to notice with the unaided eye, though the Moon is deceptively smaller than it appears: you could, for example, line up 654 ‘Supermoons’ around the local horizon from end to end.

A 'super' vs average Full Moon. Image credit: Marco Langbroek. — A ‘super’ vs average Full Moon. Image credit: Marco Langbroek.

The October Moon is also referred to by the Algonquin Native Americans as the ‘Hunter’s Moon,’ a time to use that extra illumination to track down vital sustenance as the harsh winter approaches. Very occasionally, the Harvest Full Moon falling near the September southward equinox falls in early October (as occurs next year in 2017) and bumps the Hunter’s Moon from its monthly slot.

Be sure to stalk the rising Hunter’s Moon near perigee this weekend. Of course, we’ll be shooting at our prey with nothing more than a camera, as the Full Moon rises from behind the Andalusian foothills.

October 5, 2016October 5, 2016 by David Dickinson

Seeing Double: Jupiter Returns at Dawn

Missing Jove? The largest planet in our solar system is currently on the far side of the Sun and just passed solar conjunction on September 26^th, 2016. October now sees Jupiter slowly return to the dawn sky. Follow that gas giant, as an interesting set of double shadow transits transpires in late October leading in to early November.

This particular cycle of double shadow transits involves the large Jovian moons of Europa and Ganymede.

The scene on October 24th at 23:55 UT. Image credit: Created using Starry Night Education software.

Europa and Ganymede double shadow transit season begins later this month, as both cast shadows on the Jovian cloud tops. This series of simultaneous shadow transits runs from October 17^th to November 8^th, and includes four weekly events.

The inner three large moons Io, Europa and Ganymede are in a 4:2:1 resonance. Europa orbits Jove once every 3.6 days and makes two circuits for Ganymede’s one. This means there’s a double shadow transit once every week in the current season:

The double shadow transit season of 2016. Created by author.

When can you first spy Jupiter, post solar conjunction? Catching this particular series of double shadow transits is challenging this time around, owing to the planet’s position low in the dawn twilight. The first event on October 17^th starts with Jupiter just 16 degrees west of the Sun, and the cycle ends with Jove 38 degrees west of the Sun on November 8^th.

Keep in mind, it is possible to track Jupiter up in to the daytime sky, post sunrise. To do this, you’ll need a ‘scope with a solid equatorial mount and good sidereal tracking. The trick is to lock on to Jupiter before sunrise and track it up in to the dawn sky. Be sure to physically block that dazzling rising Sun out of view behind a hill or building, and NEVER aim your telescope at the Sun!

Using this method opens up the possibility of nabbing a given double shadow event to longitudes due east of the quoted locales above.

The waning crescent Moon also passes 1.4 degrees NNE of Jupiter on October 28^th, offering another chance to spy the gas giant in the dawn sky, using the nearby crescent Moon as a guide.

The Moon and Jupiter in the daytime skies on Novemebr. — The Moon and Jupiter in the daytime skies on October 28th. Image credit: Stellarium.

And another interesting pairing is coming right up on the morning of Tuesday, October 11^th, when Mercury passes just 0.8 degrees (48′) NNE of Jupiter. Both are only 12 degrees west of the Sun at closest approach, which occurs around 10:00 UT. Still, both will appear as an interesting pseudo-double star, with Mercury shining at magnitude -1.1 and Jupiter only half a magnitude fainter at -1.6.

You can even see Jupiter coming off of solar conjunction and headed toward dawn skies courtesy of SOHO’s LASCO C3 camera:

Jupiter (arrowed) exiting the 15 degree wide field of view of SOHO's LASCO C3 camera on October 5th. Image credit: NASA/ESA/SOHO. — Jupiter (arrowed) exiting the 15 degree wide field of view of SOHO’s LASCO C3 camera on October 5th. Image credit: NASA/ESA/SOHO.

Callisto, the outermost large moon of Jupiter, ceased casting its shadow on Jupiter earlier this year on September 1^st 2016. Callisto is the only large moon that can ‘miss’ the gas giant’s cloud tops. Callisto must be involved for a triple shadow transit to occur, and the moon resumes regularly casting its shadow on Jove on December 4th, 2019.

Callisto can also experience total solar eclipses similar to those seen from the Earth during the mutual eclipse season for Jupiter’s moons, albeit shorter in duration:

And don ‘t forget: we’ve got a spacecraft currently exploring Jupiter for the next year and a half: NASA’s very own Juno.

Be sure to check out the Jovian action over the next month, gracing a dawn sky near you.

September 26, 2016 by David Dickinson

Tears of the Hunter: Our Guide to the 2016 Orionid Meteor Shower

The month of October is upon us this coming weekend, and with it, one of the better annual meteor showers is once again active: the Orionids.

In 2016, the Orionid meteors are expected to peak on October 22^nd at 2:00 UT (10:00 PM U.S. Eastern Time on October 21^st) , favoring Europe and Africa in the early morning hours. The shower is active for a one month period from October 2^nd to November 2^nd, and can vary with a Zenithal Hourly Rate (ZHR) of 10-70 meteors per hour. This year, the Orionids are expected to produce a maximum ideal ZHR of 15-25 meteors per hour. The radiant of the Orionids is located near right ascension 6 hours 24 minutes, declination 15 degrees north at the time of the peak. The radiant is in the constellation of Orion very near its juncture with Gemini and Taurus.

A gallery of Fall meteor shower radiants, including the October Orionids. Image credit: Stellarium

The Moon is at a 55% illuminated, waning gibbous phase at the peak of the Orionids, making 2016 an unfavorable year for this shower, though that shouldn’t stop you from trying. It’s true that the Moon is only 19 degrees east of the radiant in the adjacent constellation Gemini at its peak on the key morning of October 22, though it’ll move farther on through the last week of October.

In previous recent years, the Orionids produced a Zenithal Hourly Rate (ZHR) of 20 (2014) and a ZHR of 30 (2013).

The Orionid meteors strike the Earth at a moderately fast velocity of 66 km/s, and the shower tends to produce a relatively high ratio of fireballs with an r value of = 2.5. The source of the Orionids is none other than renowned comet 1/P Halley. Halley last paid the inner solar system a visit in early 1986, and will once again reach perihelion on July 28, 2061. Let’s see, by then I’ll be…

The orientation of the Earth's shadow vs, the zenith positions of the Sun, Moon and the radiant of the Orionid meteors at the expected peak of the shower on October 22nd. Image adapted from Orbitron — The orientation of the Earth’s shadow vs the zenith positions of the Sun, Moon and the radiant of the Orionid meteors at the expected during the peak of the shower on October 22nd. Image adapted from Orbitron.

Unlike most meteor showers, the Orionids display a very unpredictable maximum – many sources decline to put a precise date on the shower’s expected maximum at all. On some years, the Orionids barely top 10 per hour at their maximum, while on others they display a broad but defined peak. One 1982 study out of Czechoslovakia suggested a twin peak for this shower after looking at activity from 1944 to 1950. All good reasons to be vigilant for Orionids throughout the coming month of October.

And check out this brilliant meteor that lit up the skies over the southern UK this past weekend:

‘Tis the season for cometary dust particles to light up the night sky. Trace the path of a suspect meteor to the club of Orion, and you’ve likely sighted an Orionid meteor. But other showers showers are active in October, including:

The Draconids: Peaking around October 8th, these are debris shed by Comet 21P Giacobini-Zinner. The Draconids are prone to great outbursts, such as the 2011 and 2012 meteor storm, but are expected to yield a paltry ZHR of 10 in 2016.

The Taurids: Late October into early November is Taurid fireball season, peaking with a ZHR of 5 around October 10^th (the Southern Taurids) and November 12^th (the Northern Taurids).
The Camelopardalids: Another wildcard shower prone to periodic outbursts. 2016 is expected to be an off year for this shower, with a ZHR of 10 topping out on October 5.

And farther afield, we’ve got the Leonids (November 17^th) the Geminids (December 14^th) and the Ursids (December 22^nd) to close out 2016.

A 2015 Orionid captured by a NASA All-Sky camera atop Mt. Lemmon, Arizona. Image credit: NASA.

Observing a meteor shower like the Orionids is as simple as finding a dark site with a clear horizon, laying back and watching via good old Mark-1 eyeball. Blocking that gibbous Moon behind a building or hill will also increase your chances of catching an Orionid. Expect rates to pick up toward dawn, as the Earth turns forward and plows headlong into the meteor stream.

You can make a count of what you see and report it to the International Meteor Organization which keeps regular tabs of meteor activity.
Photographing Orionids this year might be problematic, owing to the proximity of the bright Moon, though not impossible. Again, aiming at a wide quadrant of the sky opposite to the Moon might just nab a bright Orionid meteor in profile. We like to just set our camera’s intervalometer to take a sequence of 30” exposures of the sky, and let it do the work while we’re observing visually. Nearly every meteor we’ve caught photographically turned up in later review, a testament to the limits of visual observing.

Clear skies, good luck, and send those Orionid images in the Universe Today’s Flickr forum.

September 21, 2016September 22, 2016 by David Dickinson

Occultation Palooza: The Moon Covers Aldebaran and More

This week, we thought we’d try an experiment for tonight’s occultation of Aldebaran by the Moon. As mentioned, we’re expanding the yearly guide for astronomical events for the year in 2017. We’ve done this guide in various iterations since 2009, starting on Astroguyz and then over to Universe Today, and it has grown from a simple Top 10 list, to a full scale preview of what’s on tap for the following year.

You, the reader, have made this guide grow over the years, as we incorporate feedback we’ve received.

Anyhow, we thought we’d lay out this week’s main astro-event in a fashion similar to what we have planned for the guide: each of the top 101 events will have a one page entry (two pages for the top 10 events) with a related graphic, fun facts, etc.

So in guide format, tonight’s occultation of Aldebaran would break down like this:

Wednesday, September 21^st: The Moon Occults Aldebaran

The occultation footprint of tonight's Aldebaran event. — The occultation footprint of tonight’s Aldebaran event.

Image credit Occult 4.2

The 67% illuminated waning gibbous Moon occults the +0.9 magnitude star Aldebaran. The Moon is two days prior to Last Quarter phase during the event. Both are located 109 degrees west of the Sun at the time of the event. The central time of conjunction is 22:37 Universal Time (UT). The event occurs during the daylight hours over southeast Asia, China, Japan and the northern Philippines and under darkness for India, Pakistan and the Arabian peninsula and the Horn of Africa. The Moon will next occult Aldebaran on October 19^th. This is occultation 23 in the current series of 49 running from January 29^th 2015 to September 3^rd, 2018. This is one of the more central occultations of Aldebaran by the Moon for 2016.

The view from India tonight, just before the occultation begins. Image credit: Stellarium

Fun Fact-In the current century, (2001-2100 AD) the Moon occults Aldebaran 247 times, topped only by Antares (386 times) and barely beating out Spica (220 times).

Or maybe, another fun fact could be: A frequent setting for science fiction sagas, Aldebaran is now also often confused in popular culture with Alderaan, Princess Leia’s late homeworld from the Star Wars saga.

Like it? Thoughts, suggestions, complaints?

Now for the Wow! Factor for tonight’s occultation. Aldebaran is 65 light years distant, meaning the light we’re seeing left the star in 1951 before getting photobombed by the Moon just over one second before reaching the Earth.

There are also lots of other occultations of fainter stars worldwide over the next 24 hours, as the Moon crosses the Hyades.

And follow that Moon, as a series of 20 occultations of the bright star Regulus during every lunation begins later this year on December 18th.

Gadi Eidelheit managed to catch the March 14^th, 2016 daytime occultation of Aldebaran from Israel:

And also in the ‘Moon passing in front of things’ department, here’s a noble attempt at capturing a difficult occultation of Neptune by the Moon last week on September 15th, courtesy of Veijo Timonen based in Hämeenlinna Finland:

Lets see, that’s a +8^th magnitude planet next to a brilliant -13^th magnitude Moon, one million (15 magnitudes) times brighter… it’s amazing you can see Neptune at all!

Last item: tomorrow marks the September (southward) equinox, ushering in the start of astronomical fall in the northern hemisphere, and the beginning of Spring in the southern. The precise minute of equinoctial crossing is 14:21 UT. In the 21^st century, the September equinox can fall anywhere from September 21^st to September 23rd. Bob King has a great recent write-up on the equinox and the Moon.

Here's EVERY occultation of Aldebaran from 2015 through 2018. (Click to enlarge) Credit: Occult 4.2. — Here’s EVERY occultation of Aldebaran from 2015 through 2018. (Click to enlarge) Credit: Occult 4.2.

Don’t miss tonight’s passage of Aldebaran through the Hyades, and there’s lots more where that came from headed into 2017!

September 12, 2016September 17, 2016 by David Dickinson

Bloostar: Launching Satellites via Balloon

AistechSat-1 — The recent flight of Aistechsat-1. Image credit: Zero2Infinity.

Is there a better way to get to space? Current traditional methods using expendable rockets launching from the surface of the Earth are terribly inefficient. About 90% of the bulk and mass of what you see on the launch pad is expended in the first few minutes of the mission, just getting the tiny payload above the murk of Earth’s atmosphere and out of the planet’s gravity well.

One idea that’s been out there for a while is to loft a launch platform into the upper atmosphere, and simply start from there. One Spanish-based company named Zero2infinity plans to do just that.

Recently, on May 20^th, 2016, Zero2infinity lofted Aistech’s first satellite into the upper atmosphere, aboard its Sub-Orbital Platform in Near Space balloon system. Zero2infinity uses these Near Space balloons to carry client payloads up above 99% of the Earth’s atmosphere. This is a cheap and effective way to get payloads into a very space-like environment.

These near Space Balloon platforms typically reach an altitude of 28 kilometres (17 miles) above the surface of the Earth. For reference, the Armstrong Line (where the boiling point of water equals human body temperature) starts 18 kilometers up, and the Kármán line — the internationally recognized boundary where space begins — starts at an altitude of 100 kilometers, or 62 miles up.

Most satellites in Low Earth Orbit (LEO) go around the Earth 300 to 600 kilometers up, and the International Space Station resides in a 400 by 400 kilometer standard orbit.

The mission of Aistechsat-1 is to “provide thermal images of the Earth and also help with maritime and aeronautical tracking,” Zero2infinity representative Iris Silverio told Universe Today via email. Zero2infinity plans on conducting another balloon test with Aistechsat-1 later this month on an as yet to be announced date. The final decision all hinges on the weather and the wind speeds aloft.

Aistech envisions a constellation of 25 such nanosatellites encircling the planet.

Zero2infinity also has a grander vision: eventually launching satellites into Low Earth Orbit via balloon. Known as Bloostar, this system would loft a three stage rocket with the company’s existing and proven Near Space balloon technology. The ‘launch’ would occur high in the upper atmosphere, as the engines take over to get the payload into orbit.

Getting there; the Bloostar approach to low Earth orbit. Image credit: Zero2Infinity.

The idea is certainly attractive. Dubbed a ‘shortcut to space,’ the three engine booster rings depicted are a fraction of the size of typical rocket stages. The toroid ring-shaped stages are simply nestled one inside the other, like Russian dolls. Zero2infinity also envisions scaling its ‘Bloon’ platform for micro and nano payloads… and I’ll bet that a Bloostar atmospheric launch will be an interesting spectacle to watch with binoculars from the ground, especially around dawn or dusk.

Another possible advantage includes a much more spacious payload nose cone, meaning no more folding of satellites for launch and unfolding them in orbit. More than a few payloads have suffered setbacks because of this, including the Galileo mission to Jupiter, whose main antenna failed to unfurl completely in 1990.

According to an email discussion with Zero2infinity representative Silverio, the first commercial Bloostar launch is set for 2019, with possible orbital trials starting as early as 2018. Bloostar deployments will occur off the coast of the Canary Islands in the Atlantic. The initial Bloostar launcher will deploy payloads up to 75 kilograms in a 600 kilometer orbit around the Earth.

Rise of the Rockoons

The idea of conducting launches via balloon, known as a ‘rockoon,’ has been around for a while. Thus far, only sub-orbital launches have been conducted in this manner.

A Deacon rockoon shortly after a U.S. Navy shipboard launch. Public Domain image.

The first balloon-based launch of a rocket occurred on August 9^th, 1953, when a Deacon rockoon successfully carried out a sub-orbital launch high over the Atlantic Ocean. Though several companies have kicked around the idea of launching an orbital satellite via balloon-based platform, Zero2infinity might just be the first to actually accomplish it. The United States Department of Defense has considered the idea of launching satellites (and satellite-killing missiles) via the U.S. Air Force’s high flying F-15 Eagle aircraft. Orbital Sciences does currently use its Pegasus-XL rocket carried aloft by a L1011 aircraft to place satellites in orbit. That’s how NASA’s NuSTAR X-ray telescope got into space in 2012.

There is one main problem facing balloon-based space launches: weather. Unlike aircraft, balloons are often at the whims of the winds aloft, and sometimes stubbornly refuse to go where you want them to. Often, an orbital launch will need to target a precise azimuth heading, a tricky sort of pointing to do from underneath a balloon. Still, we’ve already seen precedent for overcoming this in the effective pointing of balloon-based telescopes, such as the BLAST telescope.

Bloostar might just provide an innovative and cost-effective way to head into orbit, very soon.

-Check out this 2014 article from Universe Today on Zero2Infinity.

-Zero2Infinity also caught last year’s total solar eclipse over the Arctic from aloft.

September 6, 2016September 6, 2016 by David Dickinson

An Impalpable Penumbral Eclipse

Hey, how ’bout that annular eclipse last week? Some great images flooded in to Universe Today, as the final solar eclipse for 2016 graced the African continent. This not only marked the start of the second and final eclipse season for 2016, but it also set us up for the final eclipse of the year next week.

The path of next week's penumbral eclipse through the Earth's shadow. Adapted from NASA/GSFC/F. Espenak. — The path of next week’s penumbral eclipse through the Earth’s shadow. Adapted from NASA/GSFC/F. Espenak.

We’re talking about the penumbral lunar eclipse coming up next week on September 16^th, 2016. this sort of eclipse occurs when the Moon just misses the dark inner core (umbra) of the Earth’s shadow, and instead, drifts through its relatively bright outer cone, known as the penumbra. Though not the grandest show as eclipses go, astute observers should notice a subtle light tea-colored shading of the Full Moon, and perhaps the ragged dark edge of the umbra on the northwestern limb of the Moon as it brushes by around mid-eclipse.

The visibility map for next week's eclipse. Image credit: NASA/GSFC/Fred Espenak. — The visibility map for next week’s eclipse. Image credit: NASA/GSFC/Fred Espenak.

The entirety of the eclipse will be visible from the region surrounding the Indian Ocean on the evening of Friday, September 6^th. Viewers in Australia, New Zealand and Japan will see the eclipse transpire at moonset, and the eclipse will get underway at moonrise for observers in western Africa and Europe.

The eclipse runs from first contact at 16:55 Universal Time (UT) to 20:54 UT when the Moon quits the Earth’s shadow almost four hours later. Mid-eclipse occurs at 18:55 UT, with the Moon 91% immersed in the Earth’s outer shadow.

Tales of the Saros

This particular eclipse is member 9 of the 71 lunar eclipses in saros series 147. This saros began on July 2^nd 1890 and runs through to the final eclipse in the cycle on May 1^st 2990. It will produce its very first partial eclipse next time around on September 28^th 2034, and its first total lunar eclipse on June 6^th, 2449.

Why penumbrals? Aren’t they the ultimate non-event when it comes to eclipses? Like with much of observational astronomy, a penumbral lunar eclipse pushes our skills as a visual athlete to the limit. Check out the waxing gibbous Moon the night before the eclipse, then the Moon the night of the event. If you didn’t know any better, could you tell the difference from one night to the next? Often, the camera can see what the eye can’t. Photographing the Moon before, during and after a penumbral eclipse will often bring out the subtle shading on post-comparison. You’ll want to photograph the Moon when its high in the sky and free of atmospheric distortion low to the horizon, which tends to discolor the Moon. Such a high-flying Moon during mid-eclipse favors the Indian Subcontinent this time around. We’ve yet to see a good convincing time-lapse documenting a penumbral eclipse, though such a feat is certainly possible.

See anything... shady going on? Here's the penumbral lunar eclipse from this past March. Image credit and copyright: Neeraj Ladia — See anything… shady going on? Here’s the penumbral lunar eclipse from this past March. Image credit and copyright: Neeraj Ladia

When is an eclipse… not an eclipse? By some accounts, the Moon underwent a very shallow penumbral one cycle ago on August 18^th, 2016, though the brush past the shadow was so slight that many lists, including the NASA’s GSFC eclipse page omitted it. Three eclipses (a lunar partial and a penumbral, or two penumbrals and one solar) can occur in one eclipse season, if the nodes of the Moon’s orbit where it intersects the ecliptic fall just right. This last occurred in 2013, and will happen again in 2020.

And when there’s a lunar eclipse, there’s also a Full Moon. The September Full Moon is the Harvest Moon, providing a few extra hours of illumination to get the crops in. This year, the Harvest Moon falls just six days from the equinox on September 22^nd, marking the start of astronomical Fall in the northern hemisphere and Spring in the southern. The relative ecliptic angle also ensures that moonrise only slides back by a slight amount each evening for observers in mid-northern latitudes around the Harvest Moon.

Can’t wait til the next eclipse? Well, 2017 has four of ’em: an annular on February 26th favoring South America, two lunars (another penumbral on February 11^th and a partial on August 7^th) and oh yeah, there’s a total solar eclipse crossing the United States on August 21st. And the next total lunar eclipse? The dry spell is broken on January 31^st, 2018, when a total lunar eclipse favoring the Pacific Rim occurs. Yeah, we got spoiled with four back-to-back lunar eclipses during the Blood Moon tetrad of 2014-2015…

Read Dave Dickinson’s eclipse-fueled sci-fi tales Exeligmos, Shadowfall, The Syzygy Gambit and Peak Season.

August 30, 2016 by David Dickinson

Our Guide to This Week’s ‘Ring of Fire’ Annular Eclipse

In Africa this week? The final solar eclipse of 2016 graces the continent on Thursday, September 1st. This eclipse is annular only, as the diminutive Moon fails to fully cover the disk of the Sun.

The 99.7 kilometer wide path crosses the African countries of Gabon, Republic of the Congo, Democratic Republic of the Congo, Tanzania, Mozambique and Madagascar. The antumbra (the ‘ring of fire path of the shadow annulus as viewed from Earth) touches down in the southern Atlantic at 7:20 Universal Time (UT) on September 1^st, before racing across Africa and departing our fair planet over the Indian Ocean over four hours later at 10:55 UT. Partial phases for the eclipse will be visible across the African continent as far north as southern Morocco, Egypt and the southwestern portion of the Arabian peninsula.

Path. Credit: Xavier Jubier. — The path of this week’s eclipse across Africa. Credit: Xavier Jubier.

Tales of the Saros

This eclipse is member 39 of 71 solar eclipses for saros 135, which runs from July 5^th, 1331 to August 17^th, 2593. This series finally produces its first total solar eclipse on March 29, 2359.

A daguerreotype of an annular eclipse from 1854, part of the same saros 154 cycle. Public domain image.

Annular eclipses occur when the Moon is too distant to cover the Sun as seen from the Earth. The Moon reaches apogee, or its most distant point from the Earth on September 6th, just five days after New and the September 1st eclipse.

How common (or rare) are solar eclipses, annular or total? It’s worth noting that as the 2017 total solar eclipse crossing the contiguous United States approaches, creationist websites are again promoting the idea that the supposed ‘perfection’ of solar eclipses is evidence for intelligent design. If solar eclipses are an example of a higher plan to the cosmos, they’re not a very good one… in fact, in our current epoch, partial eclipses, to include annulars, are much more prevalent. If, for example, the Moon’s orbit was aligned with the ecliptic, we’d see two eclipses – one lunar and and one solar – every month, a much rarer circumstance… a creator could have really used that to really get our attention. And Earth isn’t alone in hosting total solar eclipses: in our own solar system, you can make a brief visit to Jupiter’s large moons and also witness total solar eclipse perfection.

Unlike a total solar eclipse, proper eye protection must be worn throughout all stages of an annular eclipse. We witnessed annularity from the shores of Lake Erie back in 1994, and can attest that a few percent of the Sun is still surprisingly bright. The tireless purveyors of astronomy over at Astronomers Without Borders are working to distribute eclipse glasses to schools and students along the eclipse path.

An animation of Thursday's eclipse. Credit: NASA/GSFC. — An animation of Thursday’s eclipse. Credit: NASA/GSFC.

Are you in the path of this week’s annular eclipse? Let us know, and send those images in to Universe Today on Flickr.

We’ll most likely see more than a few images of the eclipse from space as well. And no, we’re not talking about the cheesy composite that now makes its rounds during every eclipse… solar observing satellites to include the European Space Agency’s Proba-2 and the joint JAXA/NASA Hinode mission typically capture several successive eclipses as they observe the Sun from their vantage point in low Earth orbit.

At this stage, we only know of one webcast set to broadcast the eclipse live: the venerable Slooh website.

Let us know if you’re planning on setting up an ad hoc live webcast of the eclipse, even from outside the path of annularity.

And of course, the big question on every eclipse-chaser’s mind is: when’s the next one? Well, we’ve got a subtle penumbral eclipse on September 16^th, 2016, and then the next solar eclipse is another annular favoring Argentina, Chile and the west coast of southern Africa on February 26^th, 2017.

Don’t miss this week’s annular solar eclipse, either live online or in person, for a chance to marvel at a celestial phenomenon we all share in time and space.

-Eclipse… science fiction? Yup… read Dave Dickinson’s eclipse-fueled tales Peak Season, Exeligmos, Shadowfall and The Syzygy Gambit.

August 24, 2016August 24, 2016 by David Dickinson

Tales of Two Asteroid Occultations: Io, Nemausa Cast Shadows Over North America

Don't blink... an artist's conception of an asteroid blocking out a distant star. Image credit: NASA.

Up for a challenge? Over the next two weekends, two asteroid occultations pass over North America. These are both occulting (passing in front of) +7^th magnitude stars, easy targets for even binoculars or a small telescope. These events both have a probability score of 99-100%, meaning the paths are known to a high degree of accuracy. These are also two of the more high profile asteroid occultations for 2016.

Here’s the lowdown on both events:

The path of the 85 Io event. Image credit: Steve Preston/Asteroid Occultation Updates.

On the morning of Saturday, August 27^th, the +10^th magnitude asteroid 85 Io occults a +7.5 magnitude star (TYC 0517-00165-1). the maximum predicted duration for the event is 28 seconds, and the maximum predicted brightness drop is expected to be 3 magnitudes. The ‘shadow’ will cross North America from the northeast to the southwest starting over Quebec at 4:27 Universal Time (UT), crossing Ontario and Michigan’s upper peninsula at 4:30 UT, and heading south over Oklahoma, Texas, and Mexico at 4:36 UT. The action takes place in the constellation Aquarius, with the Moon at a 28% waning crescent.

A wide field finder view for the 85 Io event. Image credit: Stellarium

Discovered by C.H.F. Peters on September 19^th, 1865, 85 Io is about 180 kilometers in diameter, as measured by an occultation in late 1995.

Next, on the morning of Saturday, September 3^rd, the +11.5 magnitude asteroid 51 Nemausa occults a +7.6 mag star (HIP 8524). The maximum duration of the event along the centerline is expected to be 32 seconds in duration, with a maximum drop of four magnitudes. Said shadow will cross western Canada at9:42 UT, and the U.S. crossing runs from 9:49 to 9:55 UT. The action takes place in the constellation Pisces. The Moon phase is a slim 4% waxing crescent during the event.

Discovered in 1858 by A. Laurent observing from Nîmes, France, 51 Nemausa occulted a bright star in 1979. In fact, there’s evidence from previous occultation to suggest the 51 Nemausa may possess a tiny moon… could it show up again during the September 3rd event?

Observing asteroid occultations is really a modern sub-specialty of amateur and even professional astronomy. To predict such an occurrence, the orbit of the asteroid or occulting body and the precise position of the star need to be known to a pretty high degree of precision. This required the advent of modern astrometry and massive computing power. If any casual sky observer noticed a naked eye star wink out way back when pre-mid 20th century, it’s lost to history.

The first successfully predicted and observed occultation of a star by an asteroid was the +8.2 magnitude star SAO 112328 by 3 Juno on February 19, 1958. Less than two dozen such events were observed right up through to 1980. Today, hundreds of such events are predicted worldwide each year.

Next month’s expected data release from the ESA’s Gaia mission should refine our stellar position and parallax knowledge even further, and fine-tune predictions of future asteroid occultations.

And speaking of occultations, some great observations were made of the July 29th, 2016 lunar grazing occultation of Aldebaran across the United States. The Moon occults Aldebaran for every lunation in 2016 into 2017, and we get another shot favoring the southern U.S. in the daytime on August 25th.

Observing an asteroid occultation is a challenge, requiring an observer acquiring and monitoring the correct star at the precise time of the event. If possible (i.e. weather permitting) familiarize yourself with the star field a night or two prior to the event. I usually have a precise audio time signal such as WWV radio running in the background.

The shape of 51 Nemausa from the 2014 event. Image credit: Occult 4.2.

Why occultations? Well, if enough observations can be gathered, a sort of shadow profile of the occulting space rock can be made, with each observation representing a chord. Even negative ‘misses’ along the edge of the path help. Tiny moons of asteroids have even been discovered this way, as the distant star winks out multiple times.

The International Occultation Timing Association wants your observation. You can, with a little practice, make usable observations visually, though most observers tend to video record events.

Don’t miss these asteroid occultations and more, coming to a sky worldwide near you!

August 16, 2016 by David Dickinson

One Year to the 2017 Total Solar Eclipse

https://www.flickr.com/photos/auraluu/7085004603/in/photolist-bN5v2M-dufbuU-pzUHQi-nZQkxQ-6KdhJ7-9TLjD4-dtvX13-pidJNx-dtvUxY-dxAA8r-n8uzjn-hx1CzU-du9zKv-c4eHhw-F1szSh-hx2yTc-dv7Y5W-dubgHK-du9zB6-FvPkNQ-drNyGZ-Eg3Msj-F4kfHb-zpuHFU-yUCmvN-yuSXP5-DqsCRp-zfU1bR-zbbFV9-FrtBYE-hdVRQm-rkh8fd-dufbHG-6KGxbK-dufbmf-du9zQe-ryZmAb-FtsHpn-EAUwcK-Ct6Fma-6KLF1b-FiThUB-EEgQjh-E8uHFM-yUC28b-rqtfQ3-yTR8jt-tsa14t-rHcxrz-rXwEhJ — Totality! The view of the last total solar eclipse to cross a U.S. state (Hawaii) back in 1991. Image credit and copyright: A. Nartist (shot from Cabo San Lucas, Baja California).

One. More. Year. Quick; where will you be this time next year on August 21^st, 2017? We’re now just one year out this weekend from a fine total solar eclipse gracing the United States from coast to coast. If you think one year out is too early to start planning, well, umbraphiles (those who chase the shadow of the Moon worldwide) have been planning to catch this one now for over a decade.

The shadow of the March 9th, 2016 solar eclipse as seen from the Himawari-8 Earth-observing satellite. image credit: JAXA/JMA/Himawari/CIMSS — The shadow of the March 9th, 2016 solar eclipse (the dark spot on the right) as seen from the Himawari-8 Earth-observing satellite. Image credit: JAXA/JMA/Himawari/CIMSS.

Get set for the Great American Eclipse. The last time a total solar eclipse made landfall over a U.S. state was Hawaii on July 11^th, 1991, and the path of totality hasn’t touched down over the contiguous ‘Lower 48’ United States since February 26^th, 1979. And you have to go all the way back over nearly a century to June 8^th, 1918 to find an eclipse that exclusively crossed the United States from the Pacific to the Atlantic Coast.

The path of the 2017 total solar eclipse across the U.S. image credit and copyright: Michael Zeiler/The GreatAmercianEclipse — The path of the 2017 total solar eclipse across the U.S. Image credit and copyright: Michael Zeiler/The GreatAmercianEclipse

Totality for the August 21^st, 2017 eclipse crosses over many major cities, including Columbia South Carolina, Nashville, St. Louis and Salem, Oregon. The inner shadow of the Moon touches on 15 states as it races across the U.S. in just over an hour and a half. The length of totality is about 2 minutes in duration as the shadow makes landfall near Lincoln City, Oregon, reaches a maximum duration of 2 minutes, 42 seconds very near Carbondale, Illinois, and shrinks back down to 2 minutes and 35 seconds as the shadow heads back out to sea over Charleston, South Carolina.

The eclipse will be a late morning affair in the northwest, occurring at high noon over western Nebraska, and early afternoon to the east. ‘Getting your ass to totality,’ is a must. “But I’ve seen a partial solar eclipse,” is a common refrain, “aren’t they all the same?”

Nope. We witnessed the May 10^th, 1994 annular eclipse from the shores of Lake Erie, and can tell you that even less than 1% of the Sun’s intensity is still pretty bright, a steely blue luminosity equivalent to a cloudy day.

We crisscrossed the United States along the eclipse path back in 2014, chronicling preparations in towns such as Columbia and Hopkinsville, Kentucky. Last minute accommodation is already tough to come by, even one year out. Cabins in the Land Between the Lakes region near Paducah, Kentucky, for example, were booked full as soon as the August 21^st date became available. Think Mardi Gras and DragonCon, rolled into one. Hopkinsville also has an annual Roswell-style UFO-fest on the same date, celebrating the 1955 Kelly-Hopkinsville UFO incident.

Will it be ‘umbraphiles versus aliens?’

Out west, enticing locales include the Grand Teton National Park and Jackson Hole, Wyoming and the northern edge of the Craters of the Moon National Monument site in Idaho. It’s also worth noting that the western United States is a better bet cloud cover-wise, as afternoon summer thundershowers tend to be the norm for the southeast during late August.

Millions live within an easy day drive of the eclipse path, and it happens during prime camping season, to boot. The annual Sturgess motorcycle rally held near Rapid City, South Dakota is just one week prior to totality, and bikers returning from the pilgrimage southward could easily stop to greet the Earth’s shadow on the road home.

2017 Eclipse Panorama from Michael Zeiler on Vimeo.

There’s been talk that Cosmoquest may mount an eclipse expedition based out of Nashville, Tennessee (more to come on that).

Maintaining mobility is the best bet. Our master plan is to return to the States a week or so prior, rent a camper van from Vegas, and head northward. Like millions of Americans, this will be our first total solar eclipse, and the event promises to spark a whole new generation of umbraphiles. And stick around just seven more years, and totality will again cross the United States on August 8^th, 2024 from the southwest to the northeast. The Illinois, Missouri and Kentucky tri-state region sees this eclipse as well. This one is special for us, as it crosses over our hometown of Presque Isle, Maine. I remember looking up the next total solar eclipse over northern Maine as a kid, way back when, and figuring out just how old I would be. The top of Mount Katahdin and selected sites along the Maine Solar System model would all be choice locales to view this one. Check out this great old vid of the aforementioned 1979 eclipse over the U.S.:

We also plan on taking the veteran eclipse-chaser’s mantra of ‘experience your first eclipse; but photograph your second one.’ to heart. Lots of fascinating projects are afoot leading up to the 2017 total solar eclipse, including The Eclipse MegaMovie Project to produce a complete video documentary of the eclipse path, plans by a student group to fly and observe the eclipse from balloons during totality, proposals to replicate famous eclipse experiments and more. It’s also worth noting that the bright star Regulus will sit just one degree from the Sun during totality… perhaps someone will manage to measure its deflection via General Relativity in a manner similar to Sir Arthur Eddington’s famous 1919 observation?

Unlike the paths of most eclipses, which seem to have an affinity for wind-swept tundra or remote swaths of desert, this one is sure to draw in the ‘astronomy-curious’ and may just be the most witnessed total solar eclipse in history.

Here’s some eclipse tales and facts to ponder leading up to totality. If you caught the August 11^th, 1999 eclipse across Europe, then you saw the last eclipse in the same saros series 145. If you caught the eclipse before that in the same series on July 31^st, 1981 across northeast Asia, then you’ll complete a 54 year long triple-saros period after seeing next summer’s eclipse, known as an exeligmos. This cycle also brings the eclipse path very nearly back around to the same longitude.

Regulus near the eclipsed Sun next August. Credit: Stellarium.

The Sun is about 400 times larger than the Moon in diameter, but the Moon is 400 times closer. We’ve actually heard this fact tossed out as evidence for intelligent design, though it’s just a happy celestial circumstance of our present era. In fact, annular eclipses are now slightly more common than totals in our current epoch, and will continue to become more so as the Moon slowly recedes from the Earth. Just under a billion years ago, the very first annular eclipse of the Sun as seen from the Earth occurred, and 1.4 billion years hence, the Earth will witness one last brief total eclipse.

But you won’t have to wait that long. Don’t miss the greatest show in the universe next August!

-Check out Michael Zeiler’s (@EclipseMaps) 10-foot long strip map of the entire eclipse path.

-Eclipses, both lunar and solar have played a role in history as well.

-Curious about eclipses in time and space? Read our eclipse-fueled sci-fi tales, Exeligmos, The Syzygy Gambit and Shadowfall, with more to come!