History Archives

November 19, 2014December 23, 2015 by David Dickinson

Observing Challenge: Watch Asteroid 3 Juno Occult a +7th Magnitude Star Tonight

One of the better asteroid occultations of 2014 is coming right up tonight, and Canadian and U.S. observers in the northeast have a front row seat.

The event occurs in the early morning hours of Thursday, November 20th, when the asteroid 3 Juno occults the 7.4 magnitude star SAO 117176. The occultation kicks off in the wee hours as the 310 kilometre wide “shadow” of 3 Juno touches down and crosses North America from 6:54 to 6:57 Universal Time (UT), which is 12:54 to 12:57 AM Central, or 1:54 to 1:57 AM Eastern Standard Time.

The path of tomorrow’s occultation along with the circumstances. Credit: Steve Preston’s Asteroid Occultation website.

The maximum predicted length of the occultation for observers based along the centerline is just over 27 seconds. Note that 3 Juno also shines at magnitude +8.5, so both it and the star are binocular objects. The event will sweep across Winnipeg and Lake of the Woods straddling the U.S. Canadian border, just missing Duluth Minnesota before crossing Lake Superior and over Ottawa and Montreal and passing into northern Vermont and New Hampshire. Finally, the path crosses over Portland Maine, and heads out to sea over the Atlantic Ocean.

Don’t live along the path? Observers worldwide will still see a close pass of 3 Juno and the +7^th magnitude star as both do their best to impersonate a close binary pair. If you’ve never crossed spotting 3 Juno off of your astro-“life list,” now is a good time to try.

The position of the target star HIP43357/SAO 117176 is:

Right Ascension: 8 Hours 49’ 54”

Declination: +2° 21’ 44”

A finder chart for 3 Juno and HIP43357. Stars are noted down to +10th magnitude. Created using Starry Night Education software.

Generally, the farther east you are along the track, the higher the pair will be above the horizon when the event occurs, and the better your observing prospects will be in terms of altitude or elevation. From Portland Maine — the last port of call for the shadow of 3 Juno on dry land — the pair will be 35 degrees above the horizon in the constellation of Hydra.

The projected sky cover at the time of the occultation. Credit: NWS/NOAA.

As always, the success in observing any astronomical event is at the whim of the weather, which can be fickle in North America in November. As of 48 hours out from the occultation, weather prospects look dicey, with 70%-90% cloud cover along the track. But remember, you don’t necessarily need a fully clear sky to make a successful observation… just a clear view near the head of Hydra asterism. Remember the much anticipated occultation of Regulus by the asteroid 163 Erigone earlier this year? Alas, it went unrecorded due to pesky but pervasive cloud cover. Perhaps this week’s occultation will fall prey to the same, but it’s always worth a try. In asteroid occultations as in free throws, you miss 100% of the shots that you don’t take!

IOTA — The path of the occcultation across eastern North America. Credit: Google Earth/BREIT IDEAS observatory.

Why study asteroid occultations? Sure, it’s cool to see a star wink out as an asteroid passes in front of it, but there’s real science to be done as well. Expect the star involved in Thursday’s occultation to dip down about two magnitudes (six times) in brightness. The International Occultation Timing Association (IOTA) is always seeking careful measurements of asteroid occultations of bright stars. If enough observations are made along the track, a shape profile of the target asteroid emerges. And the possible discovery of an “asteroid moon” is not unheard of using this method, as the background star winks out multiple times.

UT-Juno Occultation — 3 Juno as imaged by the 100″ Hooker telescope at the Mt. Wilson observatory at different wavelengths using adaptive optics. Credit: NASA/JPL/The Harvard Smithsonian Center for Astrophysics.

3 Juno was discovered crossing Cetus by astronomer Karl Harding on September 1^st, 1804 from the Lilienthal Observatory in Germany. The 3^rd asteroid discovered after 1 Ceres and 2 Pallas, 3 Juno ranks 5^th in size at an estimated 290 kilometres in diameter. In the early 19^th century, 3 Juno was also considered a planet along with these other early discoveries, until the ranks swelled to a point where the category of asteroid was introduced. A denizen of the asteroid belt, 3 Juno roams from 2 A.U.s from the Sun at perigee to 3.4 A.U.s at apogee, and can reach a maximum brightness of +7.4th magnitude as seen from the Earth. No space mission has ever been dispatched to study 3 Juno, although we will get a good look at its cousin 1 Ceres next April when NASA’s Dawn spacecraft enters orbit around the king of the asteroids.

3 Juno reaches opposition and its best observing position on January 29^th, 2015.

3 Juno also has an interesting place in the history of asteroid occultations. The first ever predicted and successfully observed occultation of a star by an asteroid involved 3 Juno on February 19^th, 1958. Another occultation involving the asteroid on December 11^th, 1979 was even more widely observed. Only a handful of such events were caught prior to the 1990s, as it required ultra-precise computation and knowledge of positions and orbits. Today, dozens of asteroid occultations are predicted each month worldwide.

Observing an asteroid occultation can be challenging but rewarding. You can watch Thursday’s event with binoculars, but you’ll want to use a telescope to make a careful analysis. You can either run video during the event, or simply watch and call out when the star dims and brightens as you record audio. Precise timing and pinpointing your observing location via GPS is key, and human reaction time plays a factor as well. Be sure to locate the target star well beforehand. For precise time, you can run WWV radio in the background.

And finally, you also might see… nothing. Asteroid paths have a small amount of uncertainty to them, and although these negative observations aren’t as thrilling to watch, they’re important to the overall scientific effort.

Good luck, and let us know of your observational tales of anguish and achievement!

November 11, 2014December 23, 2015 by David Dickinson

Midway Between Storms: Our Guide to the 2014 Leonid Meteors

If there’s one meteor shower that has the potential to bring on a storm of epic proportions, it’s the Leonids. Peaking once every 33 years, these fast movers hail from the Comet 55P Temple-Tuttle, and radiate from the Sickle, or backwards “question mark” asterism in the constellation Leo. And although 2014 is an “off year” in terms of storm prospects, it’s always worth taking heed these chilly November mornings as we await the lion’s roar once again.

The prospects: 2014 sees the expected peak of the Leonids arriving around 22:00 Universal Time (UT) which is 5:00 PM EST. Locally speaking, a majority of meteor showers tend to peak in the early AM hours past midnight, as the observer’s location turns forward facing into the oncoming meteor stream. Think of driving in an early November snowstorm, with the car being the Earth and the flakes of snow as the oncoming meteors. And if you’ve (been fortunate enough?) to have never seen snow, remember that it’s the front windshield of the car going down the highway that catches all of the bugs!

This all means that in 2014, the Asian Far East will have an optimal viewing situation for the Leonids, though observers worldwide should still be vigilant. Of course, meteor showers never read online prognostications such as these, and often tend to arrive early or late. The Leonids also have a broad range of activity spanning November 6^th through November 30^th.

The November path of the radiant of the 2014 Leonids. Credit: Starry Night Education Software.

The predicted ideal Zenithal Hourly Rate for 2014 stands at about 15, which is well above the typical background sporadic rate, but lower than most years. Expect the actual sky position of the radiant and light pollution to lower this hourly number significantly. And speaking of light pollution, the Moon is a 21% illuminated waning crescent on the morning of November 17^th, rising at around 2:00 AM local in the adjacent constellation of Virgo.

The Leonids can, once every 33 years, produce a storm of magnificent proportions. The history of Leonid observation may even extend back as far as 902 A.D., which was recorded in Arab annals as the “Year of the Stars.”

But it was the morning of November 13^th, 1833 that really gained notoriety for the Leonids, and really kicked the study of meteor showers into high gear.

The night was clear over the U.S. Eastern Seaboard, and frightened townsfolk were awakened to moving shadows on bedroom walls. Fire was the first thing on most people’s minds, but they were instead confronted with a stunning and terrifying sight: a sky seeming to rain stars in every direction. Churches quickly filled up, as folks reckoned the Day of Judgment had come. The 1833 Leonid storm actually made later historical lists as one of the 100 great events in the United States for the 19^th century. The storm has also been cited as single-handedly contributing to the religious fundamentalist revivals of the 1830s. Poet Walt Whitman witnessed the 1833 storm, and the song The Stars Fell on Alabama by Frank Perkins was inspired by the event as well.

Live in Alabama? Then you may well possess a license plate that commemorates the 1833 Leonid Storm. Wikimedia Commons image in the Public Domain.

But not all were fearful. Astronomer Denison Olmsted was inspired to study the radiants and paths of meteor streams after the 1833 storm, and founded modern meteor science. The Leonids continued to produce storms at 33 year intervals, and there are still many observers that recall the spectacle that the Leonids produced over the southwestern U.S. back 1966, with a zenithal hourly rate topping an estimated 144,000 per hour!

We also have a personal fondness for this shower, as we were fortunate enough to witness the Leonids from the dark desert skies of Kuwait back in 1998. We estimated the shower approached a ZHR of about 900 towards sunrise, as a fireballs seemed to light up the desert once every few seconds.

The situation at 22:00 UT on November 17th, noting the direction of the Earth’s motion with relation to the predicted peak of the 2014 Leonid stream. Created using Stellarium.

The Leonids have subsided in recent years, and have fallen back below enhanced rates since 2002. Here’s the most recent ZHR levels as per the International Meteor Organization:

2009: ZHR=80.

2010: ZHR=32.

2011: ZHR=22.

2012: ZHR=48.

Note: 2013 the shower was, for the most part, washed out by the Full Moon.

But this year is also special for another reason.

Note that the 2014-2015 season marks the approximate halfway mark to an expected Leonid outburst around 2032. Comet 55P Tempel-Tuttle reaches perihelion on May 20^th, 2031, and if activity in the late 1990s was any indication, we expect the Leonids to start picking up again around 2030 onward.

A simulated storm on the morning of November 17th, 2032. Credit: Stellarium. — A simulated Leonid storm on the morning of November 17th, 2032. Credit: Stellarium.

Observing meteors is as simple as laying back and looking up. Be sure to stay warm, and trace the trail of any suspect meteor back to the Sickle to identify it as a Leonid. The Leonid meteors have one of the fastest approach velocities of any meteor stream at 71 kilometres per second, making for quick, fleeting passages in the pre-dawn sky. Brighter bolides may leave lingering smoke trails, and we like to keep a set of binoculars handy to examine these on occasion.

Looking to do some real science? You can document how many meteors you see per hour from your location and send this in to the International Meteor Organization, which tabulates and uses these volunteer counts to characterize a given meteor stream.

Leonids Credit: NASA — The 1997 Leonids as seen from space by the MSX satellite. Credit: NASA/JPL

And taking images of Leonid meteors is as simple as setting your DSLR camera on a tripod and taking long exposure images of the night sky. Be sure to use the widest field of view possible, and aim the camera about 45 degrees away from the radiant to nab meteors in profile. We generally shoot 30 second to 3 minute exposures in series, and don’t be afraid to experiment with manual F-stop/ISO combinations to get the settings just right for the local sky conditions. And be sure to carefully review those shots on the “big screen” afterwards… nearly every meteor we’ve caught in an image has turned up this way.

Don’t miss the 2014 Leonids. Hey, we’re half way to the start of the 2030 “storm years!”

October 27, 2014January 15, 2019 by Matt Williams

Make a Deal for Land on the Moon

Whether its asteroid prospecting, mining interests, or space tourism, a lot of industries are taking aim at space exploration. Some pioneering spirits – such as Elon Musk – even believe humanity’s survival depends on our colonizing onto other planets – such as the Moon and Mars. It’s little surprise then that lunar land peddlers have begun making deals for land on the Moon.

Continue reading “Make a Deal for Land on the Moon”

October 7, 2014December 23, 2015 by David Dickinson

REAL Images of Eclipses Seen From Space

That ‘amazing astro-shot that isn’t’ is making the rounds of ‘ye ole web again.

You know the one. “See an Amazing Image of an Eclipse… From SPACE!!!” screams the breathless headline, with the all-too-perfect image of totality over the limb of the Earth, with the Milky Way thrown in behind it for good measure.

As the old saying goes, if it looks too good to be true, it probably is. Sure, the pic is a fake, and it’s been debunked many, many times since it was first released into the wild a few years back. But never let reality get in the way of a good viral meme. As eclipse season 2 of 2 gets underway tonight with a total lunar eclipse followed by a partial solar eclipse on October 23rd both visible from North America, the image is once again making its rounds. But there’s a long history of authentic captures of eclipses from space that are just as compelling. We’ve compiled just such a roll call of real images of eclipses seen from space:

A partial solar eclipse as captured by SDO. Credit: NASA/SDO.

The Solar Dynamics Observatory:

Launched in 2010, The Solar Dynamics Observatory or SDO is NASA’s premier orbiting solar observatory. But unlike Sun-staring satellites based in low Earth orbit, SDO’s geosynchronous orbit assures that it tends to see a cycle of partial solar eclipses twice a year, roughly around the equinoxes. And like many satellites, SDO also passes into the Earth’s shadow as well, offering unique views of a solar eclipse by the limb of the Earth from its vantage point.

Hinode:

A joint mission between NASA and JAXA (the Japanese Aerospace Exploration Agency) launched in 2006, Hinode observes the Sun from low Earth orbit. As a consequence, it nearly has a similar vantage point as terrestrial viewers and frequently nabs passages of the Moon as solar eclipses occur. Such events, however, are fleeting; moving at about eight kilometres per second, such eclipses last only seconds in duration!

Catching the passage of the Moon during a brief partial eclipse. Credit: ESA.

Proba-2:

Like Hinode, Proba-2 is the European Space Agency’s flagship solar observing spacecraft based in low Earth orbit. It also catches sight of the occasional solar eclipse, and these fleeting passages of the Moon in front of the Earth happen in quick multiple cycles. Recent images from Proba-2 are available online.

Eclipses from the ISS:

The International Space Station isn’t equipped to observe the Sun per se, but astronauts and cosmonauts aboard have managed to catch views of solar eclipses in an unusual way, as the umbra of the Moon crosses the surface of the Earth. Such a view also takes the motion of the ISS in low Earth orbit into account. Cosmonauts aboard the late Mir space station also caught sight of the August 11^th, 1999, total solar eclipse over Europe.

NASA-GOES:

Weather satellites can, and do, occasionally catch sight of the inky black dot of the Moon’s penumbra crossing the disk of the Earth. GOES-West snapped the above image of the November 13^th, 2012, solar eclipse. The umbra of the Moon’s shadow races about 1700 kilometres per hour from west to east during an eclipse, and we can expect some interesting images in 2017 when the next total solar eclipse crosses the United States on August 21^st, 2017.

Apollo-Soyuz Test Project:

The final mission of Apollo program, the 1975 Apollo-Soyuz Test Project, also yielded an unusual and little known effort to observe the Sun. The idea was to use the Apollo command module as a “coronagraph” and have cosmonauts image the Sun from the Soyuz as the Apollo spacecraft blocked it out after undocking. Unfortunately, the Apollo thrusters smeared the exposure, and it became a less than iconic— though unusual — view from the space age.

Gemini XII and the first eclipse seen from space:

On November 12^th, 1966, a total solar eclipse graced South America. Astronauts James Lovell Jr. and Edwin “Buzz” Aldrin Jr. were also in orbit at the time, and managed to snap the first image of a solar eclipse from space. Gemini XII was the last flight of the program, and the astronauts initially thought they’d missed the eclipse after a short trajectory burn.

The 2012 transit of Venus as seen from the ISS. Credit: NASA/Don Pettit.

ISS Astronauts catch a transit of Venus:

We were fortunate that the International Space Station had its very own amateur astronomer in residence in 2012 to witness the historic transit of Venus from space. NASA astronaut Don Pettit knew that the transit would occur during his rotation, and packed a full-aperture white light solar filter for the occasion. Of course, a planetary transit meets the very loosest definition of a partial eclipse, but it’s a unique capture nonetheless.

Kaguya:

Japan’s SELENE-Kaguya spacecraft entered orbit around the Moon in 2007 and provided some outstanding imagery of our solitary natural neighbor. On February 10^th, 2009, it also managed to catch a high definition view of the Earth eclipsing the Sun as seen from lunar orbit. A rare catch, such an event occurs during every lunar eclipse as seen from the Earth.

Mars eclipse — Curiosity captures a misshapen eclipse from the surface of Mars. Credit: NASA/JPL.

An unusual eclipse… seen from Mars:

We’re fortunate to live in an epoch in time and space where total solar eclipses can occur as seen from the Earth. But bizarre eclipses and transits can also be seen from Mars. The Spirit and Opportunity rovers have witnessed brief transits of the Martian moons Phobos and Deimos across the face of the Sun, and in 2010, the Curiosity rover recorded the passage of Phobos in front of the Sun in a bizarre-potato shaped “annular eclipse”. But beyond just the “coolness” factor, the event also helped researchers refine our understanding of orbital path of the Martian moon.

The future: It’s also interesting to think of what sort of astronomical wonders await travelers as we venture out across the solar system. For example, no human has yet to stand on the Moon and witness a solar eclipse. Or how about a ring plane passage through Saturn’s rings, thus far only witnessed via the robotic eyes of Cassini? Of course, for the best views of Saturn’s rings, we recommend a vacation stay on Iapetus, the only major Saturnian moon whose orbit is inclined to the ring plane. And stick around ‘til November 10^th, 2084, and you can witness a transit of Earth, the Moon and Phobos as seen from the slopes of Elysium Mons on Mars:

Hopefully, they’ll have perfected that whole Futurama “head-in-a-jar” thing by then…

-Looking for eclipses in science fiction? Check out the author’s tales Exeligmos and Shadowfall.

September 23, 2014December 23, 2015 by David Dickinson

A Triple Occultation Bonanza: A Challenging Series of Occultations This Weekend and More

The 1st Quarter Moon occults Saturn during the last event in the series on August 5th, 2015. Sequence courtesy of Teale Britstra.

Got clear skies? This week’s equinox means the return of astronomical Fall for northern hemisphere observers and a slow but steady return of longer nights afterwards. And as the Moon returns to the evening skies, all eyes turn to the astronomical action transpiring low to the southwest at dusk.

Three planets and two “occasional” planets lie along the Moon’s apparent path this coming weekend: Mars, Saturn, Mercury and the tiny worldlets of 4 Vesta and 1 Ceres. Discovered in the early 19^th century, Ceres and Vesta enjoyed planetary status initially before being relegated to the realm of the asteroids, only to make a brief comeback in 2006 before once again being purged along with Pluto to dwarf planet status.

The Moon approaches Saturn on the evening of September 28th as seen from latitude 30 degrees north. Credit: Stellarium.

On Sunday September 28^th, the four day old Moon will actually occult (pass in front of) Saturn, Ceres, and Vesta in quick succession. The Saturn occultation is part of a series of 12 in an ongoing cycle. This particular occultation is best for Hawaiian-based observers on the evening of September 28^th. Astute observers will recall that Ceres and Vesta fit in the same 15’ field of view earlier this summer. Both are now over six degrees apart and slowly widening. Unfortunately, there is no location worldwide where it’s possible to see all (or two) of these objects occulted simultaneously. The best spots for catching the occultations of +7.8 magnitude Vesta and +9.0 magnitude Ceres are from the Horn of Africa and just off of the Chilean coast of South America, respectively. The rest of us will see a close but photogenic conjunction of the trio and the Moon. To our knowledge, an occultation of Ceres or Vesta by the dark limb of the Moon has yet to be recorded. Vesta also reaches perihelion this week on September 23^rd at 4:00 UT, about 2.2 astronomical units from the Sun and 2.6 A.U.s from Earth.

4 Vesta and 1 Ceres share the same field of view this past summer. Credit: Andrew Symes @FailedProtostar.

The reappearance of the Moon in the evening skies is also a great time to try your hand (or eyes) at the fine visual athletic sport of waxing crescent moon-spotting. The Moon passes New phase marking the start of lunation 1135 on Wednesday, September 24^th at 6:12 UT/2:12 AM EDT. First sighting opportunities will occur over the South Pacific on the same evening, with worldwide opportunities to spy the razor-thin Moon low to the west the following night. Aim your binoculars at the Moon and sweep about three degrees to the south, and you’ll spy Mercury and the bright star Spica just over a degree apart.

This week’s New Moon is also notable for marking the celebration of Rosh Hashanah, and the beginning of the Jewish year 5775 A.M. at sundown on Wednesday. The Jewish calendar is a hybrid luni-solar one, and inserted an embolismic or intercalculary month earlier this spring to stay in sync with the solar year.

Occult 4.0 — The occultation footprint of Saturn. The dashed line denotes where the event occurs in the daytime, while the solid line marks where it can be seen after sunset. Created using Occult 4.1.0.

The Moon also visits Mars and Antares on September 29^th. The ruddy pair sits just three degrees apart on the 28^th, making an interesting study in contrast. Which one looks “redder” to you? Antares was actually named by the Greeks to refer to it as the “equal to,” “pseudo,” or “anti-Mars…” Mars can take on anything from a yellowish to pumpkin orange appearance, depending on the current amount of dust suspended in its atmosphere. The action around Mars is also heating up, as NASA’s MAVEN spacecraft just arrived in orbit around the Red Planet and India’s Mars Orbiter is set to join it this week… and all as Comet A1 Siding Spring makes a close pass on October 19^th!

And speaking of spacecraft, another news maker is photo-bombing the dusk scene, although of course it’s much too faint to see. NASA’s Dawn mission is en route to enter orbit around Ceres in early 2015, and currently lies near R.A. 15h 02’ and declination -14 37’, just over a degree from Ceres as seen from Earth. The Moon will briefly “occult” the Dawn spacecraft as well on September 28^th.

Credit: Starry Night — Crowded skies: the Moon approaching Saturn, 4 Vesta, 1 Ceres and the Dawn spacecraft on the 28th. The red arrow shows the direction of the Moon. Created using Starry Night Education Software.

Be sure to keep an eye out for Earthshine on the dark limb of the Moon as our natural neighbor in space waxes from crescent to First Quarter. What you’re seeing is the reflection of sunlight from the gibbous Earth illuminating the lunar plains on the nighttime side of the Moon. This effect gives the Moon a dramatic 3D appearance and can vary depending on the amount of cloud and snow cover currently facing the Moon.

Such a close trio of conjunctions raises the question: when was the last time the Moon covered two or more planets at once? Well, on April 23^rd 1998, the Moon actually occulted Venus and Jupiter at the same time, although you had to journey to Ascension Island to witness it!

Such bizarre conjunctions are extremely rare. You need a close pairing of less than half a degree for two bright objects to be covered by the Moon at the same time. And often, such conjunctions occur too close to the Sun for observation. A great consequence of such passages, however, is that it can result in a “smiley-face” conjunction, such as the one that occurs on October 15^th, 2036:

Such an occurrence lends credence to a certain sense of cosmic irony in the universe.

And be sure to keep an eye on the Moon, as eclipse season 2 of 2 for 2014 kicks off next week, with the second total lunar eclipse of the year visible from North America.

More to come!

September 15, 2014December 23, 2015 by David Dickinson

Stalking Uranus: A Complete Guide to the 2014 Opposition Season

Uranus as seen through the automated eyes of Voyager 2 in 1986. (Credit: NASA/JPL).

It’s no joke… now is the time to begin searching the much-maligned (and mispronounced) planet Uranus as it reaches opposition in early October leading up to a very special celestial event.

Last month, we looked at the challenges of spying the solar system’s outermost ice giant world, Neptune. Currently located in the adjacent constellation Aquarius, Neptune is now 39 degrees from Uranus and widening. The two worlds had a close conjunction of just over one degree of separation in late 1993, and only long time observers of the distant worlds remember a time waaaay back in the early-1970s where the two worlds appeared farther apart than 2014 as seen from our Earthly vantage point.

In 2014, opposition occurs at 21:00 Universal Time (UT)/5:00 PM EDT on October 7^th. If this date sounds familiar, it’s because Full Moon and the second total lunar eclipse of 2014 and the ongoing lunar tetrad of eclipses occurs less than 24 hours afterwards. This puts Uranus extremely close to the eclipsed Moon, and a remote slice of the high Arctic will actually see the Moon occult (pass in front of) Uranus during totality. Such a coincidence is extremely rare: the last time the Moon occulted a naked eye planet during totality occurred back during Shakespearian times in 1591, when Saturn was covered by the eclipsed Moon. This close conjunction as seen from English soil possibly by the bard himself was mentioned in David Levy’s book and doctoral thesis The Sky in Early Modern English Literature, and a similar event involving Saturn occurs in 2344 AD.

We’re also in a cycle of occultations of Uranus in 2014, as the speedy Moon slides in front of the slow moving world every lunation until December 2015. Oppositions of Uranus — actually pronounced “YOOR-un-us” so as not to rhyme with a bodily orifice — currently occur in the month of September and move forward across our calendar by about 4 days a year.

This year sees Uranus in the astronomical constellation Pisces just south of the March equinoctial point. Uranus is moving towards and will pass within a degree of the +5.7 magnitude star 96 Piscium in late October through early November. Shining at magnitude +5.7 through the opposition season, Uranus presents a disk 3.7” in size at the telescope. You can get a positive ID on the planet by patiently sweeping the field of view: Uranus is the tiny blue-green “dot” that, unlike a star, refuses to come into a pinpoint focus.

The apparent path of Uranus from September 2014 through January 2015 across the constellation Pisces. The inset shows the tilt and orbit of its major moons across a 2′ field of view. Created by the author using Starry Night Education software.

Uranus also presents us with one of the key mysteries of the solar system. Namely, what’s up with its 97.8 degree rotational tilt? Clearly, the world sustained a major blow sometime in the solar system’s early history. In 2014, we’re viewing the world at about a 28 degree tilt and widening. This will continue until we’re looking straight at the south pole of Uranus in early 2030s. Of course, “south” and “north” are pretty arbitrary when you’re knocked back over 90 degrees on your axis! And while we enjoy the September Equinox next week on September 23^rd, the last equinox for any would-be “Uranians” occurred on December 16^th, 2007. This put the orbit of its moons edge-on from our point of view from 2006-2009 for only the third time since discovery of the planet in 1781. This won’t occur again until around 2049. Uranus also passed aphelion in 2009, which means it’s still at the farther end of its 19.1 to 17.3 astronomical unit (A.U.) range from the Sun in its 84 year orbit.

The moons of Uranus and Neptune as imaged during the 2011 opposition season. Credit: Rolf Wahl Olsen, used with permission.

And as often as Uranus ends up as the butt (bad pun) of many a scatological punch line, we can at least be glad that the world didn’t get named Georgium Sidus (Latin for “George’s Star”) after William Herschel’s benefactor, King George the III. Yes, this was a serious proposal (!). Herschel initially thought he’d found a comet upon spying Uranus, until he realized its slow motion implied a large object orbiting far out in the solar system.

A replica... Credit: — A replica of the reflecting telescope that Herschel used to discover Uranus. Credit: Alun Salt/Wikimedia Commons image under a Creative Commons Attribution Share-Alike 2.0 license.

Spurious sightings of Uranus actually crop up on star maps prior to Herschel’s time, and in theory, it hovers juuusst above naked eye visibility near opposition as seen from a dark sky site… can you pick out Uranus without optical assistance during totality next month? Hershel and Lassell also made claims of spotting early ring systems around both Uranus and Neptune, though the true discovery of a tenuous ring system of Uranus was made by the Kuiper Airborne Observatory (a forerunner of SOFIA) during an occultation of a background star in 1977.

A corkscrew chart for the moons of Uranus through October. Credit: Ed Kotapish/Rings PDS node.

Looking for something more? Owners of large light buckets can capture and even image (see above) 5 of the 27 known moons of Uranus. We charted the orbital elongations for favorable apparitions through October 2014 (to the left). Check out last year’s chart for magnitudes, periods, and maximum separations for each respective moon. An occulting bar eyepiece may help you in your quest to cut down the ‘glare’ of nearby Uranus.

When will we return to Uranus? Thus far, humanity has explored the world up close exactly once, when Voyager 2 passed by in 1986. A possible “Uranus Probe” (perhaps, Uranus Orbiter is a better term) similar to Cassini has been an on- and off- proposal over the years, though it’d be a tough sell in the current era of ever dwindling budgets. Plutonium, a mandatory power source for deep space missions, is also in short supply. Such a mission might take up to a decade to enter orbit around Uranus, and would represent the farthest orbital reconnaissance of a world in our solar system. Speedy New Horizons is just whizzing by Pluto next July.

All great thoughts to ponder as you scour the skies for Uranus in the coming weeks!

September 12, 2014December 23, 2015 by Shannon Hall

Calling All Volunteers to Help Digitize Astronomical History

An example of a telescope logbook waiting to be transcribed. Credit: Smithsonian

An old brick building on Harvard’s Observatory Hill is overflowing with rows of dark green cabinets — each one filled to the brim with hundreds of astronomical glass plates in paper sleeves: old-fashioned photographic negatives of the night sky.

All in all there are more than 500,000 plates preserving roughly a century of information about faint happenings across the celestial sphere. But they’re gathering dust. So the Harvard College Observatory is digitizing its famed collection of glass plates. One by one, each plate is placed on a scanner capable of measuring the position of each tiny speck to within 11 microns. The finished produce will lead to one million gigabytes of data.

But each plate must be linked to a telescope logbook — handwritten entries recording details like the date, time, exposure length, and location in the sky. Now, Harvard is seeking your help to transcribe these logbooks.

The initial project is called Digital Access to a Sky Century at Harvard (DASCH). Although it has been hard at work scanning roughly 400 plates per day, without the logbook entries to accompany each digitized plate, information about the brightness and position of each object would be lost. Whereas with that information it will be possible to see a 100-year light curve of any bright object within 15 degrees of the north galactic pole.

The century of data allows astronomers to detect slow variations over decades, something otherwise impossible in today’s recent digital era.

Assistant Curator David Sliski is especially excited about the potential overlap in our hunt for exoplanets. “It covers the Kepler field beautifully,” Sliski told Universe Today. It should also be completed by the time next-generation exoplanet missions (such as TESS, PLATO, and Kepler 2) come online — allowing astronomers to look for long-term variability in a host star that may potentially affect an exoplanet’s habitability.

There are more than 100 logbooks containing about 100,000 pages of text. Volunteers will type in a few numbers per line of text onto web-based forms. It’s a task impossible for any scanner since optical character recognition doesn’t work on these hand-written entries.

Harvard is partnering with the Smithsonian Transcription Center to recruit digital volunteers. The two will then be able to bring the historic documents to a new, global audience via the web. To participate in this new initiative, visit Smithsonian’s transcription site here.

September 8, 2014December 23, 2015 by David Dickinson

The Nicaragua Crater: The Result of a Meteorite Impact or Not?

The suspect crater on the outskirts of Managua. Credit: AP/BBC News

By now, you’ve seen the pictures.

As astronomers tracked the close pass of Near Earth Asteroid 2014 RC this weekend, reports came out of Nicaragua that a possible meteorite struck near the capital of Managua.

Details are still sketchy, but government sources cite reports of a loud bang and ground tremor late Saturday night on September 6^th. Later images circulating late Sunday evening showed a crater 12 metres wide and 5.5 metres deep on a remote section of the international airport at Managua, which also hosts a local air force installation.

A closer look at the Managua crater. Credit: AFP/BBC News.

Reports state that the impact went off “like a bomb,” and Wilfried Strauch of the Nicaragua Institute of Earth Studies has already gone on record as being “convinced it was a meteorite.” Investigators are currently scouring the alleged impact site for debris.

This has also sparked a lively discussion across forums and social media: is the crater the result of an extraterrestrial impactor?

Of course, cosmic coincidences can and do happen. Last year, the close passage of asteroid 2012 DA14 was upstaged by the explosion of a 20-metre asteroid over the city of Chelyabinsk on the very same day. And though the two were conclusively proven to be unrelated, they did serve to raise general human awareness that, yes, large threatening rocks do indeed menace the Earth. And ironically, the aforementioned asteroid 2014 RC was about the same size as the Chelyabinsk asteroid, which snuck up on the Earth undetected from a sunward direction.

But Ron Baalke, a software engineer at the Jet Propulsion Laboratory has posted an update to the close pass by asteroid 2014 RC on the NASA’s Near Earth Object website, saying, “Since the explosion in Nicaragua occurred a full 13 hours before the close passage of asteroid 2014 RC, these two events are unrelated.”

Baalke also noted that “no eyewitness accounts or imagery have come to light of the fireball flash or debris trail that is typically associated with a meteor of the size required to produce such a crater.”

The epic airburst over Chelyabinsk as captured via dashcam. (Still from video).

There are a few other problems with the Managua crater, though of course, we’d love to be proven wrong. Many observers have noted that the crater does not appear to look fresh, and the trees and soil around it appear to be relatively undisturbed. A first visual impression of the site looks more like a ground slump or sinkhole than an impact, or perhaps an excavation. Others have also noted the similarity of the crater with a military blast, a very good possibility with an air force base nearby.

Meteorite Men’s own Geoff Notkin has voiced doubts as to the authenticity of the meteor crater on Twitter.

Of course, it’s possible (though unlikely) that the impactor struck the site from straight overhead, leaving the area around it undisturbed. As with meteor showers, an impactor striking the Earth before local midnight would be coming at the planet from behind at a lower combined velocity.

Color me skeptical on this one. Still, we’ve been wrong before, and it’s always a boon for science when a new meteorite fall turns out to be real. Many have already cited the similarities between the Managua crater and the Carancas event in 2007 in Peru near Lake Titicaca that was initially considered dubious as well.

But again, it’s highly improbable that the Managua event is related to 2014 RC, however, which made its closest pass over the southern hemisphere near New Zealand many hours later at 18:18 UT on Sept 7th. We ran a recent simulation of the pass in Starry Night from the vantage point of the asteroid, and you’ll note that Central America is well out of view:

It’s also curious that no still images or video of the Managua event have yet to surface. This is strange, as it occurred on a Saturday night near a capital city of 2.4 million. The weather over Managua was partly cloudy that night, and generally, a security camera or two usually catches sight of the fireball.

We also did a check through any upcoming space junk reentries, which also proved to be a poor fit for a potential suspect. The next slated reentry is a BREEZE-M Tank with the NORAD ID of 2011-074D associated with the 2011 launch of AMOS-5. This object was not overhead around the time of the Managua event, and is predicted to reenter on September 9^th at 15:15 UT +/- 14 hours.

And the same goes for the launch of AsiaSat-6 by SpaceX on Saturday night, as launches from the Cape head out eastward across the Atlantic and away from the Gulf of Mexico region.

A look at 2014 RC on the night of September 6th. Credit Gialuca Masi and the Virtual Telescope project. — A look at 2014 RC on the night of September 6th. Credit: Gianluca Masi and the Virtual Telescope Project.

Unfortunately, images and video would go a long way towards gauging a direction and final orbit of a suspect meteorite. The discovery of meteoritic debris at the site would also serve to clinch the link between the crater and a cosmic impactor as well. Or perhaps, news of the impending passage of NEO asteroid 2014 RC and the recent pass of 2014 RA the weekend prior had already primed the general public to suspect a meteor strike as an explosion was heard late in the evening… we’ve lived near bombing ranges, and are familiar with the sound of late night explosions ourselves.

Target Earth… An aerial view of Pingualuit crater in northern Quebec. Credit: NASA/Denis Sarrazin and the Pingualuit Crater Lakes project.

To be sure, the universe is a dangerous place, and errant rocks from above do on occasion have it out for any unwary species that gets in their way.

So we’ll open it up for discussion: what do you think happened on Saturday night near Managua? Was it a meteorite, or another case of a “meteor-wrong?”

September 3, 2014December 23, 2015 by David Dickinson

Get Set for the Super (or Do You Say Harvest?) Full Moon 3 of 3 for 2014

Last month's supermoon within 24 hours of perigee. Credit: Blobrana

Time to dust off those ‘what is a perigee Full Moon’ explainer posts… the supermoon once again cometh this weekend to a sky near you.

Yes. One. More. Time.

We’ve written many, many times — as have many astronomy writers — about the meme that just won’t die. The supermoon really brings ‘em out, just like werewolves of yore… some will groan, some will bemoan the use of a modernized term inserted into the common astronomical vernacular that was wrought by an astrologer, while others will exclaim that this will indeed be the largest Full Moon EVER…

But hey, it’s a great chance to explain the weird and wonderful motion of our nearest natural neighbor in space. Thanks to the Moon, those astronomers of yore had some great lessons in celestial mechanics 101. Without the Moon, it would’ve been much tougher to unravel the rules of gravity that we take for granted when we fling a probe spaceward.

The Moon reaches Full on Tuesday, September 9^that 1:38 Universal Time (UT), which is 9:38 PM EDT on the evening of the 8^th. The Moon reaches perigee at less than 24 hours prior on September 8^th at 3:30 UT — 22 hours and 8 minutes earlier, to be precise — at a distance 358,387 kilometres distant. This is less than 2,000 kilometres from the closest perigee than can occur, and 1,491 kilometres farther away than last month’s closest perigee of the year, which occurred 27 minutes prior to Full Moon.

A Proxigean or Perigee Full “Supermoon” as reckoned by our preferred handy definition of “a Full Moon occurring within 24 hours of perigee” generally occurs annually in a cycle of three over two lunar synodic periods, and moves slowly forward by just shy of a month through the Gregorian calendar per year. The next cycle of “supermoons” starts on August 30^th, 2015, and you can see our entire list of cycles out through 2020 here.

What’s the upshot of all this? Well, aside from cluttering inboxes and social media with tales of the impending supermoon this weekend, the rising Moon will appear 33.5’ arc minutes in diameter as opposed to its usually quoted average of 30’ in size. And remember, that’s in apparent size as seen from our Earthly vantage point… can you spy a difference from one Full Moon to the next? Fun fact: the rising Moon is actually farther away from you to the tune of about one Earth radius than when it’s directly overhead at the zenith.

Fed up with supermoon-mania? The September Full Moon also has a more pedestrian name: The Harvest Moon. Actually, this is the Full Moon that falls nearest to the September Equinox, marking the start of the astronomical season of Fall in the northern hemisphere and Spring in the southern. In the current first half of the 21st century, the September Equinox falls on the 22^nd or 23^rd, meaning that the closest Full Moon (and thus the Harvest Moon) can sometimes fall in October, as last happened in 2009 and will occur again in 2017. In this instance, the September Full Moon would then be referred to as the Corn Moon as reckoned by the Algonquins, and is occasionally referred to as the Drying Grass Moon by Sioux tribes. In 2014, the Harvest Full Moon “misses” falling in October by about 32 hours!

The waning gibbous Moon of July 14th, 2014- shortly after the first supermoon of the year. Credit: Blobrana.

So, why is it known as the Harvest Moon? Well, in the age before artificial lighting (and artificial light pollution) the rising of the Full Moon as the Sun sets allowed for a few hours of extra illumination to bring in crops. In October, the same phenomenon gave hunters a few extra hours to track game by the light of the Full Hunters Moon, both essential survival activities before the onset of the long winter.

And that Full Harvest Moon seems to “stick around” on successive evenings. This is due to the relatively shallow angle of the evening ecliptic to the eastern horizon as seen from mid-northern latitudes in September.

The rising Full Moon on the evening of September 8th as seen from latitude 40 degrees north. Note the shallow angle of the ecliptic. Created using Stellarium.

Here’s a sample of rising times for the Moon this month as seen from Baltimore, Maryland at 39.3 degrees north latitude:

Saturday, September 6^th: 5:43 PM EDT

Sunday, September 7^th: 6:23 PM EDT

Monday, September 8^th: 7:05 PM EDT

Tuesday, September 9^th: 7:44 PM EDT

Wednesday, September 10^th: 8:22 PM EDT

Note the Moon rises only ~40 minutes later on each successive evening.

The Full Harvest Moon of 2013 plus aircraft. Credit: Stephen Rahn.

We’re also headed towards a “shallow year” in 2015, as the Moon bottoms out relative to the ecliptic and only ventures 18 degrees 20’ north and south of the celestial equator at shallow minimum. This is due to what’s known as the Precession of the Line of Apsides as the gravitational pull of the Sun slowly drags the orbit of the Moon round the earth once every 8.85 years. The nodes where the ecliptic and path of the Moon meet — and solar and lunar eclipses occur — also move slowly in an opposite direction of the Moon’s motion, taking just over twice as long as the Precession of the Line of Apsides to complete one revolution around the ecliptic at 18.6 years. This is one of the more bizarre facts about the motion of the Moon: its orbital tilt of 5.1 degrees is actually fixed with respect to the ecliptic as traced out by the Earth’s orbit about the Sun, not our rotational axis. Native American and ancient Northern European knew of this, and the next “Long Night’s Moon” also called a “Lunar Standstill” when the Moon rides high in the northern hemisphere sky is due through 2024-2025.

And to top it off, the Moon occults Uranus just two days after Full on September 11^th as seen from northeastern North America, Greenland, Iceland and northern Scandinavia. We’re in a cycle of occultations of Uranus by the Moon from late 2014 through 2015, and this will set the ice giant up for a spectacular close pass, and a rare occultation of the planet for a remote region in the Arctic during the October 8^th total lunar eclipse…

More to come!

September 2, 2014December 23, 2015 by David Dickinson

Hunting for “Minimoons” Orbiting Earth

It’s an engaging thought experiment.

What if Earth had multiple moons? Our world has one large natural satellite, just over a quarter the diameter, 1/50th the volume, and less than 1/80th the mass of our fair world. In fact, the Earth-Moon system has sometimes been referred to as a “binary planet,” and our Moon stands as the largest natural satellite of any planet — that is, if you subscribe to bouncing Pluto and Charon out of “the club” — in contrast to its primary of any moon in our solar system.

But what if we had two or more moons? And are there any tiny “moonlet” candidates lurking out there, awaiting discovery and perhaps exploration?

While historical searches for tiny secondary moons of the Earth — and even “moons of our Moon” — have turned up naught, the Earth does indeed capture asteroids as temporary moons and eject them back into solar orbit from time to time.

Now, a recent paper out of the University of Hawaii written in partnership with the SETI Institute and the Department of Physics at the University of Helsinki has looked at the possible prospects for the population of captured Near-Earth asteroids, and the feasibility of detecting these with existing and future systems about to come online.

The hunt for spurious moons of the Earth has a fascinating and largely untold history. Arthur Upgren’s outstanding book Many Skies devotes an entire chapter to the possible ramifications of an Earth with multiple moons… sure, more moons would be a bane for astrophotographers, but hey, eclipses and transits of the Sun would be more common, a definite plus.

In 1846, astronomer Frederic Petit announced the discovery of a tiny Earth-orbiting moon from Toulouse observatory. “Petit’s Moon” was said to orbit the Earth once every 2 hours and 44 minutes and reach an apogee of 3,570 kilometres and a perigee of just 11.4 (!) kilometres, placing it well inside the Earth’s atmosphere on closest approach.

A slightly more believable claim came from astronomer Georg Waltemath in 1898 for a moon 700 kilometres in size — he claimed it was, of course, a very dark body and not very easily visible — orbiting the Earth at about 2.5 times the distance of the Moon. Waltemath even made an announcement of his discovery, and claimed to have found a third moon of the Earth for good measure.

And a much more dubious claim came from the astrologer Walter Gornold in 1918 of a secondary moon, dubbed Lilith. Apparently, then (as now) astrologers never actually bothered to look at the skies…

Turns out, our large Moon makes a pretty good goaltender, ejecting —and sometimes taking a beating from — any tiny second moon hopeful. Of course, you can’t blame those astronomers of yore entirely. Though none of these spurious moons survived the test of observational verification, these discoveries often stemmed from early efforts to accurately predict the precise motion of the Moon. Astronomers therefore felt they were on the right track, looking for an unseen perturbing body.

Fast forward to the 21^st century. Quasi-moons of the Earth, such as 3753 Cruithne, have horseshoe-shaped orbits and seem to approach and recede from our planet as both orbit the Sun. Similar quasi-moons of Venus have also been discovered.

And even returning space junk can masquerade as a moon of Earth, as was the case of J002E3 and 2010 QW1, which turned out to be boosters from Apollo 12 and the Chinese Chang’e-2 missions, respectively.

What modern researchers are looking for are termed Temporarily Captured Orbiters, or TCOs. The study notes that perhaps an average of a few dozen asteroids up to 1 to 2 metres in size are in a “steady state” population that may be orbiting the Earth at any given time on an enter, orbit, and eject sort of conveyor belt. Estimates suggest that a large 5 to 10 metre asteroid is captured every decade so, and a 100 metre or larger TCO is temporarily captured by the Earth every 100,000 years. The study also estimates that about 1% occasionally hit the Earth. And though it wasn’t a TCO, the ability to detect an Earthbound asteroid before impact was demonstrated in 2008 with the discovery of 2008 TC3, less than 24 hours prior to striking in the Sudanese desert.

“There are currently no projects that are solely looking for minimoons at this time,” lead researcher Bryce Bolin of the University of Hawaii told Universe Today. “There are several surveys, such as PanSTARRS, the Catalina Sky Survey and the Palomar Transit Factory that are currently in operation that have the capability of discovering minimoons.”

We’re getting better at this hazardous asteroid detection business, that’s for sure. The researchers modeled paths and orbits for TCOs in the study, and also noted that collections may “clump” at the anti-sunward L2 opposition point, and the L1 sunward point, with smaller distributions located at the east and west quadrature points located 90 degrees on either side of the Earth. The L2 point in particular might make a good place to start the search.

Ironically, systems such as LINEAR and PanSTARRS may have already captured a TCO in their data and disregarded them in their quest for traditional Near Earth Objects.

“Surveys such as PanSTARRS/LINEAR utilize a filtration process to remove artifacts and false positives in the data as it gets processed through the data pipeline,” Researcher Bryce Bolin told Universe Today. “A common method is to apply a rate of motion cut… this is effective in eliminating many artifacts (which) tend to have a rate of motion as measured by the pipeline which is very high.”

Such systems aren’t always looking for fast movers near Earth orbit that can produce a trail or streak which may reassemble space junk or become lost in the gaps over multiple detection devices. And speaking of which, researchers note that Arecibo and the U.S. Air Force’s Space Surveillance System may be recruited in this effort as well. To date, one definite TCO, named 2006 RH120 has been documented orbiting and departing from the vicinity of the Earth, and such worldlets might make enticing targets for future manned missions due to their relatively low Delta-V for arrival and departure.

Future asteroid mission. Credit: NASA — An artist’s concept of a possible future asteroid mission near Earth. Credit: NASA.

PanSTARRS-2 saw first light last year in 2013, and is slated to go online for full science operations by the end of 2014. Eventually, the PanSTARRS system will employ four telescopes, and may find a bevy of TCOs. The researchers estimate in the study that a telescope such as Subaru stands a 90% chance of nabbing a TCO after only five nights of dedicated sweeps of the sky.

Finally, the study also notes that evidence miniature moonlets orbiting Earth may lurk in the all sky data gathered by automated cameras and amateur observers during meteor showers. Of course, we’re talking tiny, dust-to-pebble sized evidence, but there’s no lower limit as to what constitutes a moon…

And so, although moons such a “Lilith” and “Petit’s Moon” belong to the annuals of astronomical history, temporary “minimoons” of Earth are modern realities. And as events such as Chelyabinsk remind us, it’s always worthwhile to hunt for hazardous NEOs (and TCOs) that may be headed our way. Hey, to paraphrase science fiction author Larry Niven: unlike the dinosaurs, we have a space program!

Read more about the fascinating history of moons that never were and more in the classic book The Haunted Observatory.