Skywatching Archives

April 30, 2018 by David Dickinson

By Jove: Jupiter at Opposition for 2018

A recent capture of Jupiter from April 21st. Image credit and copyright: Efrain Morales.

It’s a question I’ve fielded lots this weekend leading up to last night’s April Pink Full Moon, and one I expect we’ll get again tonight: “What’s that bright star near the Moon?”

That bright “star” is actually a planet, the king of them all as far as our Solar System is concerned: Jupiter. May also ushers in Jupiter observing season, as the planet reaches opposition on May 9th, rising in the east opposite to the setting Sun to the west. Jupiter now joins Venus in the dusk sky, ending the planetary drought plaguing many an evening star party.

Looking east tonight (April 30th) at 9 PM local. Created using Stellarium.

All planetary news seems to lead back to Jupiter this season. Just last week, we wrote about a recent study, suggesting that Jupiter actually gets hit by asteroids and comets on a much more regular basis than astronomers thought.

It’s always worth keeping a sharp eye on Jupiter. Shining a magnitude -2.5 near opposition, you can even pick Jupiter out against the deep blue daytime sky… if you know exactly where to look for it. The Moon visits Jupiter once every orbit, and the next time to try this feat of visual athletics is on May 27th, just before sunset.

Jupiter is 4.4 astronomical units (658 million kilometers) distant at opposition this year, and presents a disk 45” across.

At the eyepiece, Jupiter presents a roiling upper atmosphere, completing an amazing rotation once every 9.9 hours. This is not only fast enough to give Jove a noticeable equatorial bulge at its equator, but you can also observe and image Jupiter in its entirety in just one clear evening.

One of the first things that becomes apparent observing Jupiter at low power are its retinue of four Galilean moons. These are, from interior outward: Io, Europa, Ganymede and Callisto. Speedy Io takes just 1.8 days to orbit Jupiter once, while outermost Callisto takes a leisurely 16.7 days to make one circuit around Jupiter. Not only is it fun to note the changes in configuration of Jupiter’s major moons from night to night, but it’s interesting to watch them cast shadows onto Jupiter’s cloud tops and alternately disappear and reappear in and out of Jupiter’s shadow.

Two shadows crossing the face of Jupiter on July 30th, 2018. Created using Stellarium.

A few times a year, you can catch two moons casting a shadow on Jupiter at once. These usually happen in seasons, with the next pair involving Io and Europa (the most frequent transiters) set to occur on July 30th, 2018. Rarer still are triple transits, which last occurred on January 24th, 2015 and will happen next on March 20th, 2032. You’ll never see a quadruple transit though… and the outermost moon Callisto is the only one that can “miss” Jupiter, as it does in 2018.

The celestial scene changes, too, like a spotlight cast over the stage of the sky. At opposition, for example, Jupiter and its moons cast their respective shadows straight back, nearly behind them from our perspective. Watch how this changes, however, as Jupiter heads towards quadrature at 90 degrees elongation east of the Sun on August 6th, 2018 and we see Jupiter and its moons cast their shadows to the side.

Danish astronomer Ole Rømer noted a discrepancy in the timings of shadow transits near opposition versus quadrature and correctly realized that light from the events was actually taking time to transit from Jupiter to his telescope on Earth, and made the first crude measurement of the speed of light in 1676.

Crank up the magnification, and the Great Red Spot will pop into view if it’s turned Earthward. Though this centuries-long storm has been shrinking in recent years, it also seems to be condensing and reddening once again, versus the pale salmon color its exhibited as of late. How old is the Great Red Spot? Will it disappear this century, disappointing legions of school kids who diligently crayon in a ruby red eye on Jove?

One thing is for sure; the face of Jove does change over time. Another interesting example is the disappearing act that Jove’s Southern Equatorial Belt (SEB) makes every decade or so… this last occurred during 2010 season, and we may soon be due again. It would be an amazing scientific opportunity if this were to occur before NASA’s Juno spacecraft completes its mission this summer. Our question: why does the SEB disappear, while the NEB seems to be a permanent fixture on Jove?

All mysteries presented by the largest planet in our solar system, this opposition season 2018.

-Track the positions of Jupiter’s moons and the Great Red Spot using the SETI PDS Rings node, S&T’s app and Project Pluto.

April 26, 2018 by David Dickinson

Asteroids Smack Jupiter More Often Than Astronomers Thought

Jupiter Impact — Pow: The July 1994 impact of Comet Shoemaker-Levy 9 on Jupiter, captured by the Hubble Space Telescope. Credit: R. Evans/J. Trauger/H. Hammel/HST Comet Science Team/NASA.

Are you keeping a eye on Jupiter? The King of the Planets, Jove presents a swirling upper atmosphere full of action, a worthy object of telescopic study as it heads towards another fine opposition on May 9^th, 2018.

Now, an interesting international study out of the School of Engineering in Bilbao, Spain, the Astronomical Society of France, the Meath Astronomical Group in Dublin Ireland, the Astronomical Society of Australia, and the Esteve Duran Observatory in Spain gives us a fascinating and encouraging possibly, and another reason to keep a sharp eye on old Jove: Jupiter may just get smacked with asteroids on a more regular basis than previously thought.

The study is especially interesting, as it primarily focused in on flashes chronicled by amateur imagers and observers in recent years. In particular, researchers focused on impact events witnessed on March 17^th 2016 and May 26^th, 2017, along with the comparison of exogenous (of cosmic origin) dust measured in the upper atmosphere. This allowed researchers to come up with an interesting estimate: Jupiter most likely gets hit by an asteroid 5-20 meters in diameter (for comparison, the Chelyabinsk bolide was an estimated 20 meters across) 10 to 65 times every year, though researchers extrapolate that a dedicated search might only nab an impact flash or scar once every 0.4 to 2.4 years or so.

Compare this impact rate with the Earth, which gets hit by a Chelyabinsk-sized 20-meter impactor about once every half century or so. Incidentally, we know this impact rate on Earth better than ever before, largely due to U.S. Department of Defense classified assets in space continually watching for nuclear tests and missile launches, which also pick up an occasional meteor “photobomb.”

Small asteroid impacts over the span of the Earth over a 20 year period. NASA/Planetary Science.

One reason we may never have witnessed a meteor impact on Jupiter is, astronomers (both professional and amateur) never thought to look for them. The big wake-up call was the impact of Comet Shoemaker-Levy 9 in July 1994, an event witnessed by the newly refurbished Hubble Space Telescope as the resulting impact scars were easily visible in backyard telescopes for weeks afterward. Back in the day, speculation was rampant in the days leading up to the impact: would the collision be visible at all? Or would gigantic Jupiter simply gobble up the tiny comet fragments with nary a belch?

Australian amateur astronomer Anthony Wesley also caught an interesting impact (scar?) in 2009, and every few years or so, we get word of an elusive flash reported on the Jovian cloudtops, sometimes corroborated by a secondary independent observation or a resulting impact scar, and sometimes not.

An impact scar (top center on the disk) on Jupiter, captured on July 19th, 2009. Image credit: Anthony Wesley.

Of course, there are factors which will lower said ideal versus the actual observed impact rate. There’s always a month or so a year, for example, when Jupiter is near solar conjunction on the far side of the Sun, and out of range for observation. Also, we only see half of the Jovian disk from our Earthly perspective at any given time, and we’re about to lose our only set of eyes in orbit around Jupiter – NASA’s Juno spacecraft – later this summer, unless there’s a last minute mission extension.

On the plus side, however, Jupiter is a fast rotator, spinning on its axis once every 9.9 hours. This also means that near opposition, you can also track Jupiter through one full rotation in a single evening.

Finding Jupiter: looking eastward tonight at around 11PM local. Credit Stellarium.

Then there’s the planet’s location in the sky: Currently, Jupiter’s crossing the southern constellation of Libra, and opposition for Jove moves about one astronomical constellation eastward along the ecliptic a year. Jupiter will bottom out along the ecliptic in late 2019, and won’t pop back up north of the celestial equator until May 2022. And while it’s not impossible for northern observers to keep tabs on Jupiter when it’s down south, we certainly get more gaps in coverage around this time.

Hale-Bopp’s close inbound passage near Jupiter in 1996. Credit: NASA/JPL-Horizons.

Should we hail Jove as a protective ‘cosmic goal-tender,’ or fear it as the bringer of death and destruction? There are theories that Jupiter may be both: for example, Jupiter altered the inbound path of Comet Hale-Bopp in 1997, shortening its orbital period from 4,200 to 2,533 years. The 2000 book Rare Earth even included the hypothesis of Jupiter as a cosmic debris sweeper as one of the factors for why life evolved on Earth… if this is true, it’s an imperfect one, as Earth does indeed still get hit as well.

All reasons to keep an eye on Jupiter in the 2018 opposition season.

-See something strange? The ALPO Jupiter observers section wants to know!

April 12, 2018 by Bob King

See The Finest Sights Before You Die With “Wonders of the Night Sky”

Framed by stars reflected by water, a kayaker leans back to take in the grandeur of the night sky. The photo appears in my new book in the chapter titled “Stars on Water.” Credit: Bob King

After months parked in front of a computer, I’m thrilled to announce the publication of my new book. The full title is — get ready for this — Wonders of the Night Sky You Must See Before You Die: The Guide to Extraordinary Curiosities of Our Universe. In a nutshell, it’s a bucket list of cosmic things I think everyone should see sometime in their life.

I couldn’t live without the sky. The concerns of Earth absorb so much of our lives that the sky provides an essential relief valve. It’s a cosmos-sized wilderness that invites both deep exploration and reflection. Galileo would kill to come back for one more clear night if he could.

Cover of Wonders of the Night Sky. 57 different sights are featured.

To me, the stars are irresistible, but my sense is that many people don’t look up as much as they’d like. We forget. Get busy. Bad weather intervenes. So I thought hard about the essential “must-sees” for any watcher of the skies. Some are obvious, like a total solar eclipse or Saturn through a telescope, but others are just as interesting — if sometimes off the beaten path.

For instance, we always hear about asteroids in the news. What does a real one look like from your own backyard? I give directions and a map for seeing the brightest of them, Vesta. And if you’ve ever looked up at the Big Dipper and wondered how to find the rest of the Great Bear, I’ll get you there. I love red stars, so you’re going to find out where the reddest one resides and how to see it yourself. There’s also a lunar Top 10 for small telescope users and chapters on the awesome Cygnus Star Cloud and how to see a supernova.

You can see most of the sky wonders described in the book from the northern hemisphere, but I included several essential southern sights like the Southern Cross.

The 57 different sights are a mix of naked-eye objects plus ones you’ll need an ordinary pair of binoculars or small telescope to see. At the end of each chapter, I provide directions on how and when to find each wonder. Because we live in an online world with so many wonderful tools available for skywatchers, I make extensive use of mobile phone apps that allow anyone to stay in touch with nearly every aspect of the night sky.

For the things that need a telescope, the resources section has suggestions and websites where you can purchase a nice but inexpensive instrument. Of course, you may not want to buy a telescope. That’s OK. I’m certain you’ll still enjoy reading about each of these amazing sights to learn more about what’s been up there all your life.

Northern spectacles like the Perseus Double Cluster can’t be missed.

While most of the nighttime sights are visible from your home or a suitable dark sky site, you’ll have to travel to see others. Who doesn’t like to get out of the house once in a while? If you travel north or south, new places mean new stars and constellations. I included chapters on choice southern treats like Alpha Centauri, the Southern Cross and the Magellanic Clouds, the closest and brightest galaxies to our own Milky Way.

One of my favorite parts of the book is the epilogue, where I share a lesson my dog taught me about the present moment and cosmic time. I like to joke that if nothing else, the ending’s worth the price of the book.

The author with his 10-inch Dobsonian reflector. Credit: Linda Hanson

The staff at Page Street Publishing did a wonderful job with the layout and design, so “Wonders” is beautiful to look at. Everyone who’s flipped through it likes the feel, and several people have even commented on how good it smells! And for those who understandably complained that the typeface in my first book, Night Sky with the Naked Eye, made it difficult to read, I’ve got good news for you. The new book’s type is bigger and easy on the eyes.

“Wonders” is 224 pages long, printed in full color and the same size as my previous book. Unlike the few but longer chapters of the first book, the new one has many shorter chapters, and you can dip in anywhere. I think you’ll love it.

The publication date is April 24, but you can pre-order it right now at Amazon, BN and Indiebound. I want to thank Fraser Cain here at Universe Today for letting me tell you a little about my book, and I look forward to the opportunity to share my night-sky favorites with all of you.

April 11, 2018 by David Dickinson

New Saturn Storm Emerging?

Are you following the planets this season? The planetary action is about to heat up, as Jupiter, Saturn and Mars all head towards fine oppositions over the next few months.

Spying the Storms of Saturn

Astrophotographer Damian Peach raised the alarm on Twitter this past week of a possible bright storm emerging of the planet Saturn. The spot was noticeable even with the naked eye and in the raw video Peach captured, a sure sign that the storm was a biggie.

Though outbursts of clusters of white spots on the surface of Saturn aren’t uncommon, it’s rare to see one emerge at such a high latitude. The storm had faded considerably the next observing session Peach performed on April 5th, though observers should remain vigilant.

Saturn Storm 2 — A storm subsiding? The followup view a few days later on April 5th. Image credit and copyright: Damian Peach.

It’s sad to think: Cassini and our eyes in the outer solar system are no more… and the situation will probably remain this way for some years to come. Juno also wraps up its mission at Jupiter (pending extension) this year, and New Horizons visits its final destination Ultima Thule (neé 2014 MU69) on New Year’s Day 2019, though it’ll likely continue to chronicle its journey through the outer realms of the solar system, much like the Voyager 1, 2 and Pioneer 10, 11 missions, also bound to orbit the galaxy, mute testaments to human civilization. But even though proposals for Europa Clipper, a nuclear-powered quad-copter for Saturn’s moon Titan, and a Uranus and/or Neptune Orbiter are all on the drawing board, the “gap decade” of outer solar system exploration will indeed come to pass and soon.

But dedicated amateur astronomers continue to monitor the outer solar system for changes. This month sees Saturn rising around 1:30 AM local and transiting highest to the south for northern hemisphere observers at 6:00 AM local, just before sunrise. Saturn crosses the constellation Sagittarius in 2018, bottoming out at its most southerly point this year for its 29 year path around the Sun. Saturn currently shines at +0.4 magnitude, extending 40” across (including rings) as it heads towards a fine opposition on June 27th. After opposition, Saturn formally crosses into the dusk sky. The amazing rings are an automatic draw, but last week’s storm admonishes us not to forget to check out the saffron-colored disk of Saturn itself as well. For example, I’ve always wondered: why didn’t we see the hexagon before? It’s right there festooning the northern hemisphere cap, plain as day in modern amateur images… to be sure, we’re in a modern renaissance of planetary astrophotography today, what with image stacking and processing, but surely eagle-eyed observers of yore could’ve easily picked this feature out.

And the view is changing as well, as Saturn’s rings reached a maximum tilt in respect to our line of sight of 27 degrees in 2017, and now head back towards edge-on again in 2025. And be sure to check out Saturn’s retinue of moons, half a dozen of which are easily visible in a telescope at even low power.

Finally, here’s another elemental mystery poised by Saturn related to the current storm, one that Cassini sought to solve in its final days: how fast does Saturn rotate, exactly? The usual rough guesstimate quoted is usually around 10.5 hours, but we’ve yet to pin down this fundamental value with any degree of precession.

One thing’s definitely for sure: we need to go back. In the meantime, we can enjoy the early morning views of the most glorious of the planets in our Solar System.

March 29, 2018March 29, 2018 by Bob King

Tiangong 1 Falls, Blue Moon Rises and Mars Takes Aim At Saturn

A couple watches the Moon rise from the icy shore of Lake Superior in Duluth earlier this month on March 1. Credit: Bob King

I apologize for the end-of-the-world title, but everything in it is true. And the world will still be here after it’s all done. On Friday (March 31) at 7:36 a.m. Central Time, the Moon will be full for the second time this month, which makes it a Blue Moon according to popular usage. Enjoy it. What with January’s Blue Moon and now this, we’ve chewed through all our Blue Moons till Halloween 2020.

I look forward to every full moon. Watching a moonrise, we get to see all manner of amazing atmospheric distortions play across the squat, orange disk. Once the sky’s dark, its outpouring of light makes walking at night a pleasure.

When a full moon occurs in spring, it hurries south down the ecliptic, the imaginary circle in the sky defining Earth’s orbit around the Sun. For northern hemisphere skywatchers, this southward sprint delays its rising by more an hour each night, forcing a quick departure from the evening sky. And that means blessed darkness for hunting down favorite galaxies and star clusters.

Tiangong 1 and a reentry simulation

As the Moon rolls along, the hapless Chinese space station Tiangong 1 hurtles toward Earth. Drag caused by friction with the upper atmosphere continues to shrink the spacecraft’s orbit, bringing it closer and closer to inevitable breakup and incineration. Since the Chinese National Space Administration (CNSA) lost touch with Tiangong 1 in March 2016, mission control can no longer power thrusters to de-orbit it at chosen time over a safe location like the ocean. The 9.3-ton (8,500 kg) station will burn up somewhere anywhere over a vast swath of the planet between latitudes 43°N and 43°S. Included within this zone are the southern half of Europe, the southern two-thirds of the U.S., India, Australia and much of Africa and South America.

Not until the day of or even hours before will have a clear idea of when and where the station will meet its fate. According to the latest update from the Aerospace Corp., which monitors falling spacecraft, reentry is expected on Easter Sunday (April 1) at 10:30 UT / 5:30 a.m. Central Time plus or minus 16 hours. This morning (March 29), the space station is circling Earth at about 118 miles (190 km) altitude. The lowest a satelllite can still make a complete orbit of the planet is about 62 miles (100 km). Below that, break-up begins.

A high definition TV camera on an aircraft took this photo of the cargo ship ATV-1 reentering the atmosphere in September 2008. Tiangong 1 is about the same size and will likely shatter and burn in similar fashion. Credit: ESA/NASA

For up-to-the-minute updates on when to expect Tiangong 1’s orbit to decay and the machine to plunge to Earth, check out Joseph Remis’ Twitter page. Most of the space station is expected to burn up on reentry, but larger chunks might survive all the way to the ground. Since much more of the Earth’s surface is water these remnants will likely end up in the drink … but you never know. If Tiangong-1 does come down over a populated area, observers on the ground will witness a spectacular, manmade fireball day or night.

Mars (right) and Saturn pair up in Sagittarius this morning, March 29 at dawn seen from Duluth, Minn. The two planets were 2.2° apart. Details: 35mm lens, f/2.8, 13 second exposure at ISO 800. Credit: Bob King

On the quieter side but nearly as eye-catching, Mars will overtake Saturn in the coming week, passing just 1° south of the ringed planet in a thrilling dawn conjunction on April 2. If the weather forecast doesn’t look promising that morning, the two planets will remain within 2° of each other now through April 6th, providing plenty of opportunities for a look.

You can easily tell them apart by color: Mars is distinctly red-orange and Saturn looks creamy white. Both are bright at around magnitude 0 though Mars is now a hair brighter by two-tenths of a magnitude. Will you be able to see the difference?

Mars passes close to Saturn on Monday, April 2. Look low in the southeastern sky shortly before and at dawn. Try getting a picture of the lovely couple by setting up your camera on a tripod and doing a series of time exposures from 5-30 seconds at f/3.5 and ISO 800. No fancy telephoto equipment is needed: a 35-55mm lens is perfect. Created with Stellarium

In most telescopes at low magnification both planets will comfortably fit in the same field of view. Saturn’s rings are tilted nearly wide open and quite beautiful. Mars appears gibbous and though still rather small, it’s brightening rapidly and drawing closer in time for its closest approach to Earth since 2003. Wishing you clear skies!

February 26, 2018 by David Dickinson

Venus Returns to the Dusk Sky

The changing phases of Venus, from the 2013 apparition. Credit and copyright: Shahrin Ahmad (@Shahgazer)

Where have all the planets gone? The end of February 2018 sees the three naked eye outer planets – Mars, Jupiter and Saturn — hiding in the dawn. It takes an extra effort to brave the chill of a February morning, for sure. The good news is, the two inner planets – Mercury and Venus – begin favorable dusk apparitions this week, putting on a fine sunset showing in March.

Venus in 2018: Venus begins the month of March as a -3.9 magnitude, 10” disk emerging from behind the Sun. Venus is already over 12 degrees east of the Sun this week, as it begins its long chase to catch up to the Earth. Venus always emerges from behind the Sun in the dusk, lapping the Earth about eight months later as it passes through inferior conjunction between the Sun and the Earth as it ventures into the dusk sky.

Follow that planet, as Venus reaches greatest elongation at 45.9 degrees east of the Sun on August 17th. Venus occupies the apex of a right triangle on this date, with the Earth at the end of one vertice, and the Sun at the end of the other.

Not all elongations of Mercury or Venus are equal, but depend on the seasonal angle of the ecliptic, and whether they occur near aphelion or perihelion. Credit: Dave Dickinson

Mercury joins the fray in early March, as the fleeting innermost world races up to meet Venus in the dusk. March 4th is a great date to check Mercury off of your life list, as the -1.2 magnitude planet passes just 66′ – just over a degree, or twice the span of a Full Moon – from Venus. Mercury reaches greatest elongation 18.4 degrees east of the Sun on March 15^th.

And the Moon makes three on the evening of March 18th, as Mercury, Venus and the slim waxing crescent Moon form a line nine degrees long.

The Moon, Venus and Mercury – looking west at dusk on March 18th. Credit: Stellarium

It’s a bit of a cosmic irony: Venus, the closest planet to the Earth, is also eternally shrouded in clouds and appears featureless at the eyepiece. The most notable feature Venus exhibits are its phases, similar to the Moon’s. Things get interesting as Venus reaches half phase near greatest elongation. After that, the disk of Venus swells in size but thins down to a slender crescent. Venus’s orbit is tilted 3.4 degrees relative to the ecliptic, and on some years, you can follow it right through inferior conjunction from the dusk to the dawn sky. Unfortunately, this also means that Venus usually misses transiting the disk of the Sun, as it last did on June 5-6^th, 2012, and won’t do again until just under a century from now on December 10-11^th, 2117.

Small consolation prize: Mercury, a much more frequent solar transiter, will do so again next year on November 11-12th, 2019.

Amateur astronomers have, however, managed to tease out detail from the Venusian cloudtops using ultraviolet filters. And check out this amazing recent image of Venus courtesy of the Japanese Space Agency’s Akatsuki spacecraft:

Venus in the ultraviolet courtesy of JAXA’s Akatsuki spacecraft. Credit: JAXA/Akatsuki/ISAS/DARTS/Damia Bouic

It’s one of our favorite astro-challenges. Can you see Venus in the daytime? Once you’ve seen it, it’s surprisingly easily to spy… the main difficulty is to get your eyes to focus in on it without any other references against a blank sky. The crescent Moon makes a great visual aid in this quest; although the Moon’s reflectivity or albedo is actually much lower than Venus’s, it’s larger apparent size in the sky makes it stand out. Key upcoming dates to see Venus near the Moon around greatest elongation are April 17^th, May 17^th, June 16^th, July 15^th, and Aug 14^th.

Apparitions of Venus also follow a predictable eight year cycle. This occurs because 13 orbits of Venus very nearly equals eight orbits of the Earth. For example, Venus will resume visiting the Pleiades star cluster during the dusk 2020 apparition, just like it did back before 2012.

Phenomena of Venus

When does Venus appear half illuminated to you? This stage is known as dichotomy, and its actual observed point can often be several days off from its theoretical arrival. Also keep an eye out for the Ashen Light of Venus, a faint illumination of the planet’s night side during crescent phase, similar to the familiar sight seen on the crescent Moon. Unlike the Moon, however, Venus has no nearby body to illuminate its nighttime side… What’s going on here? Is this just the psychological effect of the brain filling in what the eye sees when it looks at the dazzling curve of the crescent Venus, or is it something real? Long reported by observers, a 2014 study suggests that a nascent air-glow or aurora may persist on the broiling night side of Venus.

All thoughts to ponder, as you follow Venus emerging into the dusk sky this March.

January 26, 2018 by David Dickinson

Get Set For a “Super Blue Blood Moon Total Lunar Eclipse”

Can you feel the tremor in the Force? Early next Wednesday morning internet astro-memes collide, in one of the big ticket sky events of the year, with a total lunar eclipse dubbed as — get ready — a Super Blue Blood Moon total lunar eclipse.

Specifics on the eclipse: That’s a mouthful, for sure. This is the first eclipse of 2018, and only one of two featuring totality, lunar or solar. Wednesday morning’s eclipse favors the region centered on the Pacific Rim, with regions of Asia and Australia seeing the evening eclipse at moonrise, while most of North America will see totality early Wednesday morning at moonset. Only the regions of the Canadian Maritimes and the United States east of the Mississippi misses out on the spectacle’s climax, catching a partially eclipsed Moon setting in the west at sunrise.

2018 features four eclipses overall, two lunar and two solar. Paired with this eclipse is a partial solar eclipse on February 15^th favoring the very southern tip of South America, followed by another total lunar eclipse this summer on July 27^th. The final eclipse for 2018 is a partial solar eclipse on August 11^th, favoring northern Europe and northeastern Asia.

What’s all the fuss about? Let’s dissect the eclipse, meme by meme:

Why it’s Super: Totality for this eclipse lasts 1 hour, 16 minutes and 4 seconds, the longest since April 15^th, 2014. Full Moon (and maximum duration for this eclipse) occurs at 13:30 Universal Time (UT), just 27 hours after the Moon reaches perigee the day prior on January 30^th at 9:55 UT . Note that this isn’t quite the closest perigee of the year in space and time: the January 1^st Full Moon perigee beat it out for that title by 2,429 km (1509 miles) and 23 hours.

Worldwide circumstances for Wednesday’s super blue blood moon total lunar eclipse. NASA

Why it’s Blue: This is the second Full Moon of the month, making this month’s Moon “Blue” in the modern sense of the term. This definition comes down to us thanks to a misinterpretation in the July 1943 issue of Sky & Telescope. The Maine Farmer’s Almanac once used an even more convoluted definition of a Blue Moon as “the third Full Moon in an astronomical season with four,” and legend has it, used blue ink in the almanac printing to denote that extra spurious Moon… anyone have any old Maine Farmer’s Almanacs in the attic to verify the tale?

Note that Blue Moons aren’t all that rare… the month of March 2018 also hosts two Full Moons, while truncated February 2018 contains none, sometimes referred to as a “Black Moon”.

Why All the Blood: The cone of the Earth’s umbra or dark inner shadow isn’t completely devoid of light. Instead, you’re seeing sunlight from all the Earth’s sunrises and sunsets around its limb, filtered into the shadow of the the planet onto the nearside of the Moon. Standing on the Earthward facing side of the Moon, you would witness a solar eclipse as the Earth passed between the Moon and the Sun. Unlike the neat near fit for solar eclipses on the Earth, however, solar eclipses on the Moon can last over an hour, as the Earth appears about three times larger than the disk of the Sun. And although astronauts have witnessed eclipses from space, no human has yet stood on the Moon and witnessed the ring of fire surrounding the Earth during a solar eclipse.

Tales of the Saros: For saros buffs, this eclipse is member 49 of 74 lunar eclipses for lunar saros cycle 124, stretching all the way back to August 17^th, 1152. If you caught the total lunar eclipse on January 21^st, 2000, you saw the last eclipse in this cycle. Stick around until April 18^th, 2144 AD and you can watch the final total lunar eclipse for saros 124.

Unlike total solar eclipses, lunar eclipses are leisurely affairs. The entire penumbral phase of the eclipse lasts for over 5 hours, though you probably won’t notice the subtle shading on the limb of the Moon until its about halfway immersed in the Earth’s penumbral shadow.

Not all total lunar eclipses are the same. Depending on how deep the Moon passes through the Earth’s shadow and the murkiness of the Earth’s atmosphere, the Moon can appear anywhere from a sickly orange, to a deep brick red during totality… for example, the Moon almost disappeared entirely during a total lunar eclipse shortly after the eruption of Mount Pinatubo in the early 1990s!

The color of the Moon during totality is known as its Danjon Number, with 4 being bright with a bluish cast on the outer limb of the Moon, and 0 appearing dark and deep red.

This is also one of the only times you can see that the Earth is indeed round with your own eyes as the curve of the shadow cast by our homeworld falls back across the Moon. This curve is the same, regardless of the angle, and whether the Moon is high above near the zenith, or close to the horizon.

Don’t miss the first eclipse of 2018 and the (deep breath) super blue blood Moon total lunar eclipse!

-Clouded out, or on the wrong side of the planet? Watch the January 31st eclipse live courtesy of the Virtual Telescope Project.

January 10, 2018November 7, 2018 by Paul M. Sutter

The Night Sky Magic of the Atacama

night sky above the atacama — Thousands of stars glitter in the black skies above the bone-dry desert of the Atacama in northern Chile. Photo credit: Gerhard Hüdepohl/atacamaphoto.com.

There’s nothing an astronomer – whether professional or amateur – loves more than a clear dark night sky away from the city lights. Outside the glare and glow and cloud cover that most of us experience every day, the night sky comes alive with a life of its own.

Thousands upon countless thousands of glittering jewels – each individual star a pinprick of light set against the velvet-smooth blackness of the deeper void. The arching band of the Milky Way, itself host to billions more stars so far away that we can only see their combined light from our vantage point. The familiar constellations, proudly showing their true character, drawing the eye and the mind to the ancient tales spun about them.

There are few places left in the world to see the sky as our ancestors did; to gaze in wonder at the celestial dome and feel the weight of billions of years of cosmic history hanging above us. Thankfully the International Dark Sky Association is working to preserve what’s left of the true night sky, and they’ve rightfully marked northern Chile to preserve for posterity.

Continue reading “The Night Sky Magic of the Atacama”

January 1, 2018January 15, 2018 by David Dickinson

Top 2018 Astronomy Events

The final occultation of the bright star Aldebaran by the Moon for 2017. Dave Dickinson

Happy New Year 2018.

One of the toughest choices we made last year was to not write a full astronomy guide for 2018. We’ve done this in one iteration or another now for about a decade, but an ongoing project (also astronomical in nature) has consumed most of our writing hours… but we recently realized that we can still take stock in what’s in the sky for the year ahead, and give you a sneak peek at part of our project for the end of 2018.

The Rules:

What we’ve constructed is a simple three month strip chart denoting the top astronomical events by date. The big idea was to make a latitude independent version of the familiar hourglass chart, and distill the events down to the very best.

For the top events listed below for the entire year, we considered:

–Meteor showers with a ZHR greater than 10, where the phase of the Moon is not within a week of Full;

-Oppositions of the outer planets;

-Elongations of the inner planets;

–Eclipses of the Sun and Moon;

-The closest conjunction of two naked eye planets for 2018;

-The best easily visible occultation of a bright star and a planet for 2018;

–Comets slated to reach perihelion in 2018 and forecast to break +10^th magnitude.

The Best of 2018: (events in bold are the “best of the best”)

-Meteor Showers: Lyrids (April 22), Daytime Arietids (June 7), Perseids (Aug 12), Draconid Outburst? (Oct 8) Orionids (Oct 10), Andromedids (Dec 3), Geminids (Dec 14).

-Oppositions: Mars (Jul 27), Jupiter (May 8), Saturn (Jun 27), Uranus (Oct 23), Neptune (Sep 7), Pluto (Jul 12)

-Elongations: Mercury (Jan 1, Mar, 15, Apr 29, Jul 12, Aug 26, Nov 6, Dec 15). Venus (Aug 17)

-Eclipses: A Total Lunar eclipse for Asia, Australia the Pacific and western North America (Jan 31), a partial solar for the southern tip of South America (Feb 15), a partial solar for Tasmania and southernmost Australia (Jul 13), a total lunar for South America, Europe, Africa, Australia and Asia (Jul 27), and a partial solar for Scandinavia and northern Asia (Aug 11),

-Closest conjunctions: Mars-Jupiter (January 7)

-Best occultation (planet): Mars for the southern tip of South America (Nov 16). The Moon occults 4 planets in 2018: Mercury (2), Mars (1), Venus (1), and Saturn (1)

-Best occultation (star): Aldebaran for northern Asia and Europe (Feb 23) The Moon occults Aldebaran 9 times and Regulus 5 times in 2018.

-Periodic Comets over magnitude +10 with perihelion dates: C/2016 M1 PanSTARRS (Aug 10, +9), C/2016 R2 PanSTARRS (May 9, mag +9), C/2017 S3 PanSTARRS (Aug 16, +4), 21P/Giacobini-Zinner (Sep 10, mag +4), 38P/Stephan-Oterma (Nov 11, mag +9), 46P/Wirtanen (Dec 13, mag +3)

The astronomical strip chart for the first 3 months of 2018:

Astronomical events for Jan-Mar 2018 (click the chart to see the full-sized version).

What’s Up for January-March 2018:

-The month of January 2018 kicks off with a Full Moon on the night of January 1-2, the first of two Full Moons in the month, the second of which is sometimes referred to as a Blue Moon. March 2018 also contains two Full Moons (March 2 and March 31), while the 28 day month of February lacks a Full Moon, the only month that can do so.

The Moon also continues its cycle of occultations of the bright stars Regulus and Aldebaran, favoring the following locations;

January 5- Regulus (Northern North America)

January 27-Aldebaran (Northern Pacific)

February 1- Regulus (NE Asia)

February 23- Aldebaran (northern Europe/northern Asia)

March 1-Regulus (North Atlantic)

March 22-Aldebaran (North Atlantic)

March 28-Regulus (NE Asia/Alaska)

The Moon also occults Mercury for NW North America (in the daytime) on February 15^th, then Venus just 22 hours later favoring the southern tip of South America (in the daytime), though both events are too close to the Sun to observe.

The first of two eclipse seasons for 2018 also begins in January, with a total lunar eclipse centered over the Pacific Ocean and surrounding regions on January 31^st and a 60% partial solar eclipse for the southern tip of South America on February 15.

Venus reaches superior conjunction on January 9^th, and moves into the dusk sky for a brilliant dusk apparition later in 2018. Mercury reaches greatest elongation 23 degrees west of the Sun in the dawn sky on January 2, then reaches superior conjunction on the farside of the Sun on February 17 before catching up with Venus and passing just 66′ from it on March 4.

Mars, Jupiter and Saturn remain dawn objects through the first quarter of 2018, with Mars passing just 12′ from Jupiter on January 12.

Let us know what you think, as this quarterly product is very much a work in progress… we plan on bringing you the quarterly astronomical graphic chart here on Universe Today every three months.

We’re looking forward to bringing you another great year of sky watching in 2018!

December 12, 2017December 12, 2017 by Nancy Atkinson

What is the Perfect Gift for Every Space Enthusiast? The Year in Space Calendar 2018!

What is the most wonderful time of the year? In my opinion, it is when the new Year In Space Calendars come out! This is our most-recommended holiday gift every year and whether it’s the gigantic wall calendar or the spiral-bound desk calendar, the 2018 versions don’t disappoint. They are full of wonderful color images, daily space facts, and historical references. These calendars even show you where you can look in the sky for all the best astronomical sights.

These calendars are the perfect gift every space enthusiast will enjoy all year.

The 2018 Year in Space Wall Calendar. Courtesy Steve Cariddi.

The gorgeous wall calendar has over 120 crisp color images and is larger, more lavishly illustrated, and packed with more information than any other space-themed wall calendar. It’s a huge 16 x 22 inches when hanging up.

The Year In Space calendars take you on a year-long guided tour of the Universe, providing in-depth info on human space flight, planetary exploration, and deep sky wonders. You’ll even see Universe Today featured in these calendars 🙂

The Year in Space calendars normally sell for $19.95, but Universe Today readers can buy the calendar for only $14.95 or less, with additional discounts that appear during checkout if you buy more than 1 copy at a time. Check out all the details here.

A close look at the 2018 Year in Space Wall Calendar. Courtesy Steve Cariddi.

Other features of the Year In Space calendar:
– Background info and fun facts
– A sky summary of where to find naked-eye planets
– Space history dates
– Major holidays (U.S. and Canada)
– Daily Moon phases
– A mini-biography of famous astronomer, scientist, or astronaut each month

The spiral bound desk calendar. Image courtesy Steve Cariddi.

The 136-Page Desk Calendar is available at a similar discounts. The desk calendar also includes a Monthly Sky Summary, which is a handy month-by-month list of what’s visible in the night sky, such as conjunctions, meteor showers, eclipses, planet visibility, and more. Plus there’s information on planetary exploration, including a comprehensive look at what to expect from the many planetary missions taking place in the year ahead.

Preview the calendars on the Year In Space website, where you can also get a direct link to Amazon. Because all shipping is handled through Amazon this year, currently calendars can only ship to US addresses.