Posted on by David Dickinson

101 Astronomical Events for 2017: A Teaser

A partial solar eclipse rising over the VAB. Image by author.

It’s that time of year again… time to look ahead at the top 101 astronomical events for the coming year.

And this year ’round, we finally took the plunge. After years of considering it, we took the next logical step in 2017 and expanded our yearly 101 Astronomical Events for the coming year into a full-fledged guide book, soon to be offered here for free download on Universe Today in the coming weeks. Hard to believe, we’ve been doing this look ahead in one form or another now since 2009.

This “blog post that takes six months to write” will be expanded into a full-fledged book. But the core idea is the same: the year in astronomy, distilled down into the very 101 best events worldwide. You will find the best occultations, bright comets, eclipses and much more. Each event will be interspersed with not only the ‘whens’ and ‘wheres,’ but fun facts, astronomical history, and heck, even a dash of astronomical poetry here and there.

It was our goal to take this beyond the realm of a simple almanac or Top 10 listicle, to something unique and special. Think of it as a cross between two classics we loved as a kid, Burnham’s Celestial Handbook and Guy Ottewell’s Astronomical Calendar, done up in as guide to the coming year in chronological format. Both references still reside on our desk, even in this age of digitization.

And we’ve incorporated reader feedback from over the years to make this forthcoming guide something special. Events will be laid out in chronological order, along with a quick-list for reference at the end. Each event is listed as a one- or two-page standalone entry, ready to be individually printed off as needed. We will also include 10 feature stories and true tales of astronomy. Some of these were  culled from the Universe Today archives, while others are new astronomical tales written just for the guide.

Great American Eclipse
Don’t miss 2017’s only total solar eclipse, crossing the United States! Image credit: Michael Zeiler/The Great American Eclipse.

The Best of the Best

Here’s a preview of some of the highlights for 2017:

-Solar cycle #24 begins to ebb in 2017. Are we heading towards yet another profound solar minimum?

-Brilliant Venus reaches greatest elongation in January and rules the dusk sky.

-45P/Honda-Mrkos-Pajdusakova passes 0.08 AU from Earth on February 11th, its closest passage for the remainder of the century.

-An annular solar eclipse spanning Africa and South America occurs on February 26th.

A sample occultation map from the book. Image credit: Occult 4.1.2.
A sample occultation map from the book. Image credit: Occult 4.1.2.

-A fine occultation of Aldebaran by the Moon on March 5th for North America… plus more occultations of the star worldwide during each lunation.

-A total solar eclipse spanning the contiguous United States on August 21st.

-A complex grouping of Mercury, Venus, Mars and the Moon in mid-September.

-Saturn’s rings at their widest for the decade.

Getting wider... the changing the of Saturn's rings. Image credit and copyright: Andrew Symes (@FailedProtostar).
Getting wider… the changing face of Saturn’s rings. Image credit and copyright: Andrew Symes (@FailedProtostar).

-A fine occultation of Regulus for North America on October 15th, with  occultations of the star by the Moon during every lunation for 2017.

-Asteroid 335 Roberta occults a +3rd magnitude star for northern Australia…

And that’s just for starters. Entries also cover greatest elongations for the inner planets and oppositions for the outer worlds, the very best asteroid occultations of bright stars, along with a brief look ahead at 2018.

Get ready for another great year of skywatching!

And as another teaser, here’s a link to a Google Calendar download of said events, complied by Chris Becke (@BeckePhysics). Thanks Chris!

Posted on by David Dickinson

A Lord of Rings: Saturn at Opposition 2016

Saturn 2016
Saturn in early May 2016. Image credit: Efrain Morales.

They’re back. After a wintertime largely devoid of evening worlds, the planets are once again in the evening sky. First Jupiter, then Mars have crossed opposition over the past few months, and now Saturn is set to take center stage later next week, reaching opposition at 7:00 Universal Time (UT) on the night of June 2/3rd. This places the ringed world in a position of favorable evening viewing, rising in the east as the Sun sets in the west, and riding highest near local midnight across the meridian.

Opposition 2016 sees the planet Saturn looping through the southern realm of the constellation Ophiuchus, making a retrograde run this summer at the Scorpius border before looping back and resuming eastward motion. That’s right: Saturn currently occupies the dreaded ‘13th house,’ of Ophiuchus, for all you Snake-Bearers out there. Saturn is currently at bright as it can be, at magnitude +0.04.

Saturn rising on the night of June 2nd. Image credit: Starry Night Education Software.
Saturn rising on the night of June 2nd. Image credit: Starry Night Education Software.

Saturn reaches opposition once every 378 days, as it orbits the Sun at a leisurely pace every 29.5 years. 2016 and the next few oppositions sees Saturn ‘bottoming out,’ sitting around -20 degrees south. Saturn won’t peek northward across the celestial equator again until March 2026. This places the 2016 appearance of Saturn high in the sky south of the equator, transiting about 30 degrees above the southern horizon around midnight for folks observing around 40 degrees north latitude. Saturn also begins looping towards the star-rich region of the galactic equator for a crossing it late next year in December 2017. Saturn sits 9 Astronomical Units (AU) or 1.4 billion kilometers distant on June 3rd, a slightly larger distance than usual, owing to the fact that the planet is headed towards aphelion on April 17th, 2018.

The waxing gibbous Moon passes 3.2 degrees north from Saturn on Sunday, June 19th, just a day before reaching Full.

Watch for a sudden brightening of the planet in early June, known as an ‘opposition surge’ due to what is known as the Seeliger effect. This is a coherent back-scattering of light, focusing it similar to highway retro-reflectors shining your headlights back at you at night. In this case, the Sun is the ‘headlight,’ and the millions of snowball moonlets hiding their shadows from view reaching 100% illumination are the highway retro-reflectors. The effect is subtle, to be sure, but serves to raise the brightness of the planet by about half a magnitude. This should be apparent in an animation sequence shot before, during and after over the span of a about a week. Any takers?

Almost there... the widening tilt of Saturn's rings. image credit and copyright: Andrew Symes (@failedprotostar).
Almost there… the widening tilt of Saturn’s rings. image credit and copyright: Andrew Symes (@failedprotostar).

And speaking of the rings, here’s another reason to check out Saturn this opposition 2016 season. The tilt of rings is about 26 degrees wide as seen from our Earthly perspective… about as wide as they can be. Saturn’s rings were last edge on in 2009, and reach a maximum width of 27 degrees on October 16th, 2017 before slowly heading towards edge on again in 2025.

The path of Saturn through the last half of 2016. Image credit: Starry Night Education software.
The path of Saturn through the last half of 2016. Image credit: Starry Night Education software.

At the eyepiece, Saturn shows a yellowish disk 18” extended to 43” across if you count the rings. Crank up the magnification to over 100x under good seeing, and the black thread of the Cassini division jumps into view. Saturn has 62 moons in all, with +9th magnitude Titan being the brightest. You’re looking at the most distant surface outpost of humanity, the site of the 2005 landing of the European Space Agency’s Huygens lander. Six moons are readily visible in a small telescope, while the fainter moons Hyperion and Phoebe present a challenge to owners of extreme light buckets. Also, as Saturn heads past opposition and towards eastern quadrature 90 degrees from the Sun on September 2nd, 2016, watch for the shadow of the bulk of the planet, cast back across the rings.

A sampling of the Moons of Saturn. Image credit: Stellarium.
A sampling of the Moons of Saturn. Image credit: Stellarium.

We never miss a chance to observe Saturn if it’s above the horizon. Saturn is a sure-fire crowd-pleaser for any sidewalk astronomy session, and no one forgets their first glimpse of the glorious ringed world. You can just imagine how much consternation this bizarre-looking planet must have caused Galileo. You can tell just how primitive his first telescope was, as his sketches show off Saturn as more of a two-handled ‘coffee cup’ in appearance. Christaan Huygens first deduced something of the true nature of Saturn’s rings in 1655, correctly claiming that they are physically separated from the disk.

Don’t miss Saturn at opposition next week!