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December 1, 2017December 1, 2017 by David Dickinson

Here Comes Comet Heinze for the Holidays

Comet C/2017 T1 Heinze passes near the galaxy NGC 2706 on November 25th. Image credit and copyright: Charles Bell.

Yeah, we’re still all waiting for that next great “Comet of the Century” to make its presence known. In the meantime, we’ve had a steady stream of good binocular comets over the past year both expected and new, including Comet C/2017 O1 ASASSN1, 45/P Honda-Mrkos-Pajdušáková and Comet 41P Tuttle-Giacobini-Kresák (links). Now, another newcomer is set to bring 2017 in over the finish line.

The Discovery: Astronomer Aren Heinze discovered Comet C/2017 T1 Heinze as a tiny +18^th magnitude fuzzball on the night of October 2^nd, 2017. The comet will juuust breech our “is interesting, take a look” +10^th magnitude cutoff in the final weeks of December leading into January, perhaps topping out around +8^th magnitude.

Heinze discovered his first comet as part of the Asteroid Terrestrial-Impact Last Alert System (ATLAS) search program looking for hazardous objects using the eight 50 cm Wright-Schmidt telescope array atop Haleakala and Mauna Loa in the Hawaiian Islands.

The passage of Comet Heinze through the inner solar system. Credit: NASA/JPL

The orbit for Comet Heinze is an intriguing one, and as is often the case with comets, tempts us with what could have been. Heinze will vault over the ecliptic headed northward on Christmas Day, and reaches perihelion 87 million km (0.58 AU) from the Sun on February 21^st, 2018. Closest passage from Earth for Comet Heinze is 33 million km (0.22 AU) on January 4^th, 2018, when the comet will appear to move an amazing seven degrees a day through the constellation Camelopardalis.

But it’s the southward passage of Heinze though the ecliptic on April 1st that gives us pause, only 0.0144 AU exterior of Earth’s orbit… had this occurred on July 4^th, we might’ve been in for a show, with the comet only 2.1 million kilometers away! Heinze seems like a tiny body as comets go, and there’s discussion that the comet is dynamically new and may end up shredding its nucleus all together. (link)

On a steep 97 degree inclined retrograde orbit, Comet Heinze also has a knife edge hyperbolic eccentricity of nearly 1.0. As with many long period comet, it’s tough to tell if Comet Heinze is a true denizen of our solar system, or just visiting. 2017 also saw the first asteroid whose extra-solar source was clear, as I/2017 U1 ‘Oumuamua, which passed through the inner solar system this past October.

The December path of Comet Heinze. Starry Night.

The Prospects: Currently, Comet Heinze is located highest to the south around 5AM local for northern hemisphere observers. Expect this situation to change to around 2 AM towards months end, as the comet is higher placed in the constellation Lynx come January 1^st, 2018 as it nears opposition.

Comet observer Charles Bell noted on November 27^th that Comet Heinze currently displays a short fan-shaped tail, about 88 days before perihelion.

Here’s the blow-by-blow for Comet Heinze for the next few months (passages mentioned here are to within a degree unless otherwise noted).

December

7- Crosses the celestial equator northward.

16- Passes near +3 magnitude star Zeta Hydrae.

18- Crosses into the constellation Cancer.

21- Passes near the open cluster M67.

25- Photo op: passes near the Beehive Cluster M44 and crosses the ecliptic northward.

29- Skirts the corner of the constellation Gemini and crosses into the Lynx.

January

1- May break +10^th magnitude?

1- Passes near the +4.5 magnitude star 21 Lyncis.

2- Reaches opposition.

3- Passes near the +4.5 magnitude star 2 Lyncis and into the constellation Camelopardalis.

5- Passes near the +4 magnitude star Alpha Camelopardalis.

6- Passes 31 degrees from the north celestial pole.

7- Crosses into the constellation Cassiopeia.

10-Crosses the galactic equator southward.

13- Crosses into the constellation Andromeda.

14-Crosses into the constellation Lacerta.

17- Passes near the +4.5 magnitude star 6 Lacertae.

21- Passes near the +4 magnitude star 1 Lacertae.

23- Crosses into the constellation Pegasus.

February

26- Passes near the globular cluster M15.

March

1- May drop back down below +10^th magnitude?

And though Comet Heinze won’t join their ranks, here’s a list of the great comets of the past century:

You could say we’re due.

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!

May 9, 2016May 19, 2019 by David Dickinson

Images of Today’s Transit of Mercury From Around the World

Mercury Transit — Mercury meets the Sun in Hydrogen Alpha. Image credit and copyright: Brendan Martin @HASungazer

Lead image credit: Brendan Martin.

(Note: Awesome images are being added as they come in!)

Update: Here’s two more amazing videos of yesterday’s transit of Mercury that have come our way. First: double solar transits featuring Mercury, the International Space Station and a low flying plane right here in the skies of good old planet Earth courtesy of (who else?) Thierry Legault:

And here’s one of the very few sequences we’ve seen of the transit with foreground, captured at sunset by Gadi Eidelheit based in Israel:

And finally, check out this amazing (and mesmerizing) animation of Mercury racing across the Sun, courtesy of the Big Bear Solar Observatory!

It’s not every day you get to see a planet pass in front of the Sun.

But today, skywatchers worldwide got to see just that, as diminutive Mercury passed in front of the disk of the Sun as seen from the Earth. This was the first transit of Mercury across the face of the Sun since November 8th, 2006, and the last one until November 11th, 2019. Continue reading “Images of Today’s Transit of Mercury From Around the World”

April 28, 2016 by David Dickinson

An Old Glass Plate Hints at a Potential New Exoplanet Discovery

Polluted white dwarf — An artist's conception of a 'polluted white dwarf' star, plus debris disk. Image credit: NASA.

What’s the value to exoplanet science of sifting through old astronomical observations? Quite a lot, as a recent discovery out of the Carnegie Institution for Science demonstrates. A glass plate spectrum of a nearby solitary white dwarf known as Van Maanen’s Star shows evidence of rocky debris ringing the system, giving rise to a state only recently recognized as a ‘polluted white dwarf.’ Continue reading “An Old Glass Plate Hints at a Potential New Exoplanet Discovery”

April 27, 2016April 27, 2016 by David Dickinson

Into the Red: Our Complete Guide to Mars Opposition 2016

Mars 2014 — Mars from opposition 2014. Image credit and copyright: Paul Stewart.

Ready to explore the Red Planet? Starting in May, Mars invades the evening skies of the Earth, as it heads towards opposition on May 22^nd. Not only does this place Mars front and center for prime time viewing, but we’re headed towards a cycle of favorable oppositions, with Mars near perihelion, while Earth is near aphelion. Continue reading “Into the Red: Our Complete Guide to Mars Opposition 2016”

April 19, 2016April 19, 2016 by David Dickinson

April Lunacy: Getting Ready for the Full ‘Mini-Moon’

The March 5th 2015 Mini-Moon. Image credit and copyright: Alan Dyer

Do you welcome the extra evening light of the Full Moon, or curse the additional light pollution? Either way, this week’s Full Moon on Friday April 22^nd is special. It’s the smallest Full Moon of 2016, something we here at Universe Today have christened the Mini-Moon.

Mini-Moon 2016: This year’s Mini-Moon falls on April 22^nd at 5:25 Universal Time (UT), just 13 hours and 19 minutes after lunar apogee the evening prior at 16:06 UT on April 21^st. Though apogee on the 21^st is 406,350 km distant – a bit on the far end, but the third most distant for the year by 300 km — this week’s Full Moon is the closest to apogee for 2016 time-wise. The 2015 Mini-Moon was even closer, in the 10 hour range, but you’ll have to wait until December 10^th, 2030 to find a closer occurance.

The Mini-Moon versus the 2011 Supermoon. Image credit and copyright: Ken Lord.

What is the Mini-Moon, you might ask? As with the often poorly defined Supermoon, we like to eschew the ambiguous ‘90% of its orbit’ definition, and simply refer to it as a Full Moon occurring within 24 hours of lunar apogee, or its farthest point from the Earth in its orbit.

Fun fact: the 29.55 day period from perigee to perigee (or lunar apogee-to-apogee) is known as an anomalistic month.

Mini-Moons by year for the remainder of the decade. Note that the 2020 Full Moon is also the 2nd of the month… A ‘Mini-Blue Halloween Moon?’ Image credit: Dave Dickinson

Thank our Moon’s wacky orbit for all this lunacy. Inclined 5.14 degrees relative to the ecliptic plane, the Moon returns to the same phase (say, Full back to Full) every 29.53 days, known as a synodic month. The Moon can appear 33.5′ across during perigee, and shrink to 29.4′ across near apogee.

The appearance of the Moon through one synodic period. Note that in addition to rocking back and forth (libration) and side-to-side (nutation), the Moon appears to swell and shrink in size. Wikimedia Commons graphic in the public Domain. — The appearance of the Moon through one synodic period. Note that in addition to rocking back and forth (libration) and side-to-side (nutation), the Moon appears to swell and shrink in size. Wikimedia Commons graphic in the Public Domain.

And don’t fear the ‘Green Moon,’ and rumors going ’round ye’ ole internet that promise a jaded Moon will occur in April or May; this is 100% non-reality based, seeking to join the legends of Super, Blood, and Full Moons, Black and Blue.

No. Just. No. Image faked by: David Dickinson.

The April Full Moon is also known as the Full Pink Moon to the Algonquin Indians. The April Full Moon, can, on occasion be the Full Moon ushering in Easter (known as the Paschal Moon) as per the rule established by the 325 AD council of Nicaea, stating Easter falls on the first Sunday after the first Full Moon after the fixed date of the Vernal Equinox of March 21^st. Easter can therefore fall as late as April 25th, as next occurs on 2038. The future calculation of Easter by the Church gets the Latin supervillain-sounding name of Computus.

Looking east on the evening of April 21st. Image credit: Stellarium

Of course, the astronomical vernal equinox doesn’t always fall on March 21^st, and to complicate matters even further, the Eastern Orthodox Church uses the older Julian Calendar and therefore, Easter doesn’t always align with the modern western Gregorian calendar used by the Roman Catholic Church.

The Moon can create further complications in modern timekeeping as well.

Here’s one wonderful example we recently learned of in our current travels. The Islamic calendar is exclusively based on the synodic cycle of the Moon, and loses 11 days a year in relation to the Gregorian solar calendar. Now, Morocco officially adopted Daylight Saving (or Summer) Time in 2007, opting to make the spring forward during the last weekend of March, as does the European Union to the north. However, the country reverts back to standard time during the month of Ramadan… otherwise, the break in the daily fast during summer months would fall towards local midnight.

You can see a curious future situation developing. In 2016, Ramadan runs from sundown June 5th, to July 4th. Each cycle begins with the sighting of the thin waxing crescent Moon. However, as Ramadan falls earlier, you’ll get a bizarre scenario such as 2022, when Morocco springs forward on March 27th, only to fall back to standard time six days later on April 2^nd on the start of Ramadan, only to jump forward again one lunation later on April 30th!

Morocco is the only country we’ve come across in our travels that follows such a convoluted convention of timekeeping.

Fun fact #2: the next ‘Mini-Moon’ featuring a lunar eclipse occurs on July 27^th 2018.

And the Spring Mini-Moon sets us up for Supermoon season six months later this coming October-November-December. Though lunar perigees less than 24 hours from Full usually occur as a trio, an apogee less than 24 hours from Full is nearly always a solitary affair, owing to the slightly slower motion of the Moon at a farther distance.

Don’t miss the shrunken Mini-Moon rising on the evenings of Thursday April 21^st and Friday 22^nd, coming to a sky near you.

April 12, 2016 by David Dickinson

Prelude to Transit: Catching Mercury Under Dusk Skies

Mercury and the Moon — The waxing gibbous Moon passes Mercury (low to the right). Image credit and copyright: Tavi Greiner

Have you ever seen Mercury? The diminutive innermost world takes the center stage next month, as it transits the Sun as seen from our early perspective on May 9^th. This week, we’d like to turn your attention to bashful Mercury’s dusk apparition, which sets up the clockwork celestial gears for this event. Continue reading “Prelude to Transit: Catching Mercury Under Dusk Skies”

March 27, 2016March 27, 2016 by David Dickinson

Teasing the Galactic Ghoul, Past and Present

Kaboom? An artist's conception of the ExoMars Trace Gas Orbiter separating from the Briz-M upper stage. Credit: ESA

Launch. It’s the part of spaceflight that is always the most fraught with peril, as your precious and delicate scientific package is encapsulated on top of tons of explosives, the fuze is lit, and the whole package hurls spaceward.

As noted by Bob King earlier last week on Universe Today, the European Space Agency’s ExoMars Trace Gas Orbiter underwent just such an ordeal on March 14th, as it broke the surly bonds atop a Russian Proton rocket from the Baikonur Cosmodrome, and headed towards the Red Planet with the Schiaparelli Lander affixed snug to its side. The spacecraft may have very nearly suffered a disaster that would’ve left it literally dead in space.

Don’t worry; the ExoMars Trace Gas Orbiter is OK and safely in a heliocentric orbit now, en route for an orbital insertion around the Red Planet on October 19^th, 2016. But our robotic ambassadors haven’t always been so lucky.

The Road to the Red Planet

Launching for Mars is a complex odyssey. Unlike U.S. Mars missions such as MAVEN and Curiosity, which typically launch atop an Atlas V rocket and head directly into solar orbit after launch, Russian Proton rocket launches initially enter a looping elliptical orbit around the Earth, and require a series of successive engine burns to raise the payload’s orbit for a final injection headed to Mars.

All was well as the upper stages did their job, four burns were performed, and the ExoMars Trace Gas Orbiter phoned home indicating it was in good health afterwards.

It’s what happened next that gave planners a start, and is still the source of a minor controversy.

While Russian sources tracked the Briz-M upper stage and say it worked as planned, observatories based in the southern hemisphere imaged the departure of ExoMars noted about half a dozen fragments following it. Having done its job, the Briz-M stage was to execute a maneuver after separation, placing it into a ‘graveyard’ solar orbit. Not only would this clear ExoMars on its trajectory, but the Red Planet itself.

Anatoly Zak notes in a recent article for Popular Mechanics online that the Briz-M upper stage isn’t subjected to strict sterilization measures, though its unclear if it too will reach Mars.

Solar orbit is littered with discarded boosters and spacecraft, going all the way back to the first mission to fly past the Moon and image the lunar farside, the Soviet Union’s Luna 3 in 1959. Some of these even come back on occasion to revisit the Earth as temporary moonlets, such as the Apollo 12 booster in 2002 and the Chang’e-2 booster in 2013.

And there is nothing more that the fabled ‘Galactic Ghoul’ loves than tasty Mars-bound spacecraft. Though the ExoMars Trace Gas Orbiter is in its expected trajectory to Mars as planned, it seems that the the Briz-M upper stage may have exploded seconds after spacecraft separation.

The incident is eerily similar to the fate that befell the Phobos-Grunt sample return mission. Also launched from Baikonur, the spacecraft was stranded in Earth orbit after its Fregat upper stage failed to do its job. Phobos-Grunt reentered on January 15^th, 2012 just over two months after launch, taking its container of Planetary Society-funded tardigrades scheduled to make the round trip to Mars permanently to the bottom of the Pacific Ocean instead.

The Mars 96 mission also failed to leave Earth orbit, and reentered over South America on November 16th, 1996 with a radioactive payload meant for power surface penetrators bound for the Red Planet.

The Russians haven’t had good luck with Mars landers, though they fared better landing on Venus with their Venera program… and had at least one spare Venusian Death Probe crash on Earth and fight the Six Million Dollar Man back in the 1970’s TV show, to boot.

The U.S. has actually had pretty good luck on Mars, having only lost the Mars Polar Lander for seven successful landing attempts. If successful later this year, Schiaparelli will be a first landing on Mars for any other space agency other than NASA.

And you’ll be able to explore Mars for yourself shortly, as opposition season for the Red Planet is right around the corner. Opposition for 2016 occurs on May 22nd, and we’re in for a cycle of favorable oppositions leading up to one in 2018 that’s very nearly as favorable as the historic 2003 opposition.

Space is hard, but the ExoMars Trace Gas Orbiter seems to be made of still harder stuff, the likes of which no explosion in space can kill.

Onward to Mars!

March 22, 2016 by David Dickinson

A Penumbral Lunar Eclipse Leads the Way to Easter Weekend

Can you see it? A penumbral eclipse from 2013. Image credit and copyright: Chuck Manges

Ready for Easter? The first of two lunar eclipses for 2016 occurs this week, though it’s an event so subtle, you might not notice it at first glance. We’re talking about Wednesday evening’s (morning for North America) penumbral lunar eclipse. If a total solar eclipse such as the one that crossed Indonesia and the Pacific Ocean earlier this month is the ultimate astronomical experience, then a penumbral lunar eclipse is at the other end of the spectrum, a ghostly shading on the Moon that is barely noticeable. Continue reading “A Penumbral Lunar Eclipse Leads the Way to Easter Weekend”

March 17, 2016March 18, 2016 by David Dickinson

Comet Craziness: 252P LINEAR Brightens, and a Close Pass for BA14 PanSTARRS

Comet 252P/LINEAR passes the bright star Canopus on March 13th. Image credit and copyright: Mark Sansom.

Ready for the next big ‘Comet of the Century?’ Yeah, us too. Cometary apparitions are the big unknown in backyard astronomy, an eternal uncertainty in the clockwork goings-on of the universe. Continue reading “Comet Craziness: 252P LINEAR Brightens, and a Close Pass for BA14 PanSTARRS”