Jimmy Westlake’s 2018 top celestial events
January 14, 2018
STEAMBOAT SPRINGS — The year 2018 might best be described as "The Year of the Planets." First Jupiter, then Saturn, then Mars will have a close encounter with Earth when each planet, in turn, reaches opposition this spring and summer.
The red planet, Mars, will come closer to Earth than it has since 2003. Venus returns this winter to shine as our evening star for much of the year. NASA will launch an orbiting telescope to search for undiscovered planets around thousands of nearby stars. Throw in two meteor showers, a total eclipse of the moon and a naked eye comet, and we are set for a full year of astronomical action.
This is my list of the top 10 celestial events unfolding in our skies in 2018, presented in chronological order. Most of these events can be watched and enjoyed with the unaided eye, but a few will require binoculars or a small telescope to enhance the view.
For updates on these and other celestial events this year, keep an eye on my monthly "Celestial News" column and the NASA-sponsored website SpaceWeather.com.
Jan. 31: Total eclipse of Blue Snow Super Moon
When you go to bed on Tuesday, Jan. 30, the full Blue Snow Super Moon will be shining full strength through your bedroom window. "Blue" because it is the second full moon to fall in the month of January, "Snow" because that is the name given the second full moon of the winter season, and "Super" because the full phase this month coincides with the moon's closest approach to Earth, making it appear 7 percent larger than your average full moon.
Then, at 4:48 a.m. Wednesday, Jan. 31, the Earth's dark shadow will take a bite out of the moon's upper left edge. Little by little, the shadow will engulf the moon until, by 5:51 a.m., the Blue Snow Super Moon is completely swallowed up, leaving only a blood-red ghost of a full moon.
The red color is basically the same thing as the alpenglow that you sometimes can see on the snowy mountaintops just after the sun goes down. When the mountains don't get in the way, the sunlight streams through Earth's atmosphere and out the other side, illuminating the moon with red alpenglow instead of the mountaintops.
For folks living in Northwest Colorado, totality begins when the moon is hovering only about one hand span over the western horizon. Shortly thereafter, the first rays of dawn will begin to color and brighten the sky. Totality ends at 7:08 a.m., less than 10 minutes before sunrise and only 14 minutes before the moon itself sets.
It will be an interesting challenge to see how long you can keep the totally eclipsed red ghost of the Blue Snow Super Moon in sight as the sky brightens and the stars disappear in the approaching dawn. At the onset of totality and before dawn has a chance to steal the darkness, look for the fuzzy glow of the Beehive Star Cluster, to the right of the Blue Snow Super Moon's red ghost.
Ordinary binoculars will enhance the view of both the eclipsed moon and the glittering star cluster. Our next total lunar eclipse happens before midnight on Jan. 20, 2019.
March 20: TESS mission begins
My next highlight for 2018 is the launch and beginning of an incredible space mission called TESS, the Transiting Exoplanet Survey Satellite.
NASA and the Goddard Spaceflight Center are being very tight-lipped about the actual launch date. The official statement is NET (Not Earlier Than) March 20 and NLT (Not Later Than) June 30. Assuming that everything remains on a perfect schedule, we can look for a launch of TESS onboard a SpaceX Falcon 9 rocket on or close to March 20.
You might be familiar with NASA's highly successful Kepler mission, which was the first orbiting space telescope designed specifically to search for extrasolar planets, that is, planets orbiting around other stars. Before being crippled by technical failures, Kepler had detected evidence for more than 4,200 exoplanet candidates in a patch of sky no larger than your outstretched hand at arm's length. It accomplished this by watching for tiny dips in the brightness of more than 150,000 stars caused by orbiting planets periodically eclipsing their host star.
TESS will take this transit method to the next level by completing the first all-sky survey of the 500,000 or so closest star systems to the Earth. Mission scientists expect TESS to discover several thousand new extrasolar planets, with an estimated 20 or so of those being Earth-sized rocky planets in their stars' habitable zones.
TESS is concentrating on the closest and brightest stars because that will allow scientists to tease out information about the planets' atmospheres and surface conditions. The ultimate goal is to find Earth-2 – a planet that is a twin of Earth. TESS might be the spacecraft needed to achieve that goal.
Stay tuned in the weeks and months after launch for updates on the amazing uncharted worlds that TESS discovers.
May 8: Jupiter at opposition
Jupiter is the first of three bright outer planets to reach opposition this year. Opposition is the term used to describe an outer planet's closest approach to the Earth, as both planets circle the sun. It will be at its closest point to Earth and brightest in our sky May 8, outshining every other object, except for Venus and the moon.
Jupiter will rise in the east as the sun sets in the west and will gleam brilliantly in our midnight sky with the constellation of Libra, the Scales, in the background. Jupiter will be hanging out close to Libra's alpha star, Zubenelgenubi, at the time of opposition, about 4.40 astronomical units or 409-million miles from Earth.
Any small telescope will reveal Jupiter to be a glowing white ball with two dark cloud stripes straddling its equator. It requires a larger backyard telescope to glimpse the famous Great Red Spot.
Recent studies have shown that the Red Spot is shrinking. Once wider than two Earths, Jupiter's most famous storm now is only a bit wider than one Earth. Will it continue to shrink and eventually disappear? Scientists aren't sure what's up with the Great Red Spot.
A small telescope also will reveal Jupiter's four planet-sized moons – Io, Europa, Ganymede and Callisto — discovered in 1610 by Italian astronomer Galileo Galilei.
Io is the most volcanically active world in our solar system. Europa has an ocean that contains more water than all of Earth's oceans combined. Ganymede is the largest of all the moons in our solar system, even surpassing planet Mercury in size. Callisto ranks as the third largest moon.
Watch, from night to night, as these Galilean moons constantly change their positions around Jupiter. Our own moon will pair up with Jupiter in the sky about once a month this year, on the following nights: Jan. 11, Feb. 7, March 7, April 3, April 30, May 27, June 23, July 20, Aug. 17, Sept. 13 and Oct. 11.
June 19: Venus in the Beehive star cluster
Along the celestial highway used by the moon and planets, as they whirl around their orbits, there are 12 constellations representing animals of various kinds. These are the constellations of the Zodiac: the Ram, the Bull, the Twins, the Crab, the Lion, the Virgin, the Scales, the Scorpion, the Archer, the Sea Goat, the Water Bearer and the Fish. Included in the constellations of the Zodiac are four of the skies brightest stars and four glittering star clusters that occasionally serve as pretty wallpaper for the passing planets.
One of these star clusters is Messier 44, known since ancient times as the Praesepe which is Latin for the Manger, and more recently as the Beehive. To the naked eye, the Beehive appears as a small, fuzzy smudge of light etched on the carapace of Cancer, the Crab.
For centuries, the Praesepe has been used as a weather forecaster. Roman philosopher Pliny wrote in the first century AD, "If Praesepe is not visible in a clear sky, it is a presage of a violent storm." Galileo, in 1609, was the first to aim a telescope at the misty Praesepe and resolve it into dozens of individual stars.
The Beehive contains about 1,000 stars and is one of the closest star clusters to our solar system, at a distance of 577 light years. From that distance, its 1,000 blazing suns can only manage the feeble glow of our familiar Praesepe.
When the sun goes down Tuesday, June 19, the dazzling Evening Star, Venus, will be the first to pop out in the multicolored sunset glow. However, the main event begins when darkness arrives around 10 p.m., and the faint, twinkly bees of the Beehive appear to swarm around Venus. The contrast between the sky's brightest planet and the swarming stars of the Beehive as seen through binoculars or a small telescope will provide an unforgettable cosmic moment.
Be sure to catch this event before Venus and the Beehive set in the WNW sky around 11 p.m.
June 27: Saturn at opposition
Saturn is the second bright outer planet to reach opposition in 2018. Every 378 days, the Earth gains a lap on the sluggish planet Saturn and passes directly between Saturn and the sun, placing the two planets as close together as possible.
When Saturn reaches opposition June 27, it will be 9.05 astronomical units, or 841-million miles from Earth, its closest point for 2018. Saturn will rise in the eastern sky at dusk and shine brightly all night long.
This year, Saturn shines down on us from above the famous Teapot asterism in the constellation of Sagittarius, the Archer. As fate would have it, the full Thunder Moon will rise alongside Saturn on the night of opposition.
Watch for pairings of Saturn and the Moon on these other nights in 2018: Feb. 11, March 10, April 7, May 4, May 31, July 24, Aug. 20, Sept. 17, Oct. 14 and Nov. 11.
Saturn also will have a close encounter with Mars this year. Watch during the last week of March as the two planets move closer and closer together in the predawn sky. Mars will appear closest to Saturn at about 5 a.m. April 2, when the two are only 1 degree apart. When the moon joins the pair on April 7, it will be a sight to behold.
A telescope of any size, aimed at Saturn, will reveal its beautiful icy rings and the largest of its 62 moons, Mercury-sized Titan. Dutch astronomer Christiaan Huygens discovered and named Titan in the year 1655. Today, we know Titan possesses a nitrogen rich atmosphere that is denser than Earth's and harbors great lakes of liquid methane and ethane on its frigid surface.
Saturn's rings are tilted almost at their maximum toward Earth this year, so it's a great chance to see the solar system's crown jewel at its best.
July 26: Mars at opposition
After January's total lunar eclipse, the 2018 event I am most excited about is the very close approach of the planet Mars to the Earth in July. When at its closest, Mars will shine almost twice as brightly as the dazzling planet Jupiter and, with its rusty-red color, it will be a spectacular beacon in our mid-summer sky.
It takes an average of 780 days for the faster Earth to gain a lap on Mars and pass between it and the sun for an opposition, so, close approaches to Mars only happen once every two years. Also, because of Mars' lopsided orbit, some oppositions are closer and more favorable than others.
This year's opposition on the night of July 26 is the best and closest we've had since 2003. Under the most favorable conditions, Mars can come as close as 34.6-million miles, as it did in 2003. When Mars reaches opposition July 26, it will be 35.9-million miles from Earth.
Closest approach to Mars will happen five days later, on July 31, when Mars will be 35.8-million miles from Earth. Through a medium-sized telescope, Mars will look like a flaming red ball, but look more closely and you might be able to make out some of its dark-colored deserts and maybe even its snowy white south polar ice cap. Glimpsing these Martian features through your own backyard telescope is a thrill that doesn't present itself but once every 15 years, so make the most of it.
Mars will be glowing prominently in the southern constellation of Capricornus, the Sea Goat, during opposition this year. The moon will pair up with the Red Planet once per month on these nights in 2018: Feb. 9, March 9, April 7, May 6, June 3, June 30, July 26, Aug. 22, Sept. 19, Oct. 17, Nov. 15 and Dec. 14.
Before dawn on the morning of April Fool's Day, Mars will pass less than one-half degree north of the Great Sagittarius Star Cluster, M22, a colossal ball containing a million stars and residing 10,000 light years from Earth — no foolin'! If you own a telescope, aim it at Mars that morning for a spectacular view of the Red Planet and star cluster.
As a bonus, ringed planet Saturn also will appear only one degree from Mars that morning. One month after opposition, on Aug. 26, watch as Mars poses beside a tiny crucifix-shaped star pattern called the Terrebellum. Binoculars will offer the best view of Mars meeting the Terebellum.
Aug. 12 to 13: Perseid meteor shower
The annual Perseid meteor shower almost always makes my top 10 list of celestial events. It is one of the most reliable and prolific of our annual meteor showers and occurs during the warm nights of summer. There's nothing like lying back on the ground, staring straight up into the sky, and counting the meteors as they zip by.
We experience this shower of "shooting stars" every August because the Earth plows head-on into the dust stream left behind by a comet named Swift-Tuttle. Discovered in 1862 by Lewis Swift and Horace Tuttle, this dirty snowball orbits the sun once every 133 years, leaving a trail of dust in its wake. The particles shed by the comet are exceedingly small, not much larger than grains of sand, but when they hit the Earth's atmosphere traveling 37 miles per second, they burn up in brief but brilliant streaks of light.
If the sky is dark and clear, a single observer usually can count between 60 and 90 meteors per hour, about one a minute, during the shower's peak hours. I've noticed that the Perseids tend to shoot across the sky in brief flurries of two or three, with a few minutes of calm in between.
The meteors will seem to spring out of the constellation of Perseus in the northeastern sky, beneath the familiar "W" shaped star pattern of Cassiopeia. This year, the night of peak activity is expected to be Aug. 12 and 13, but a large number of meteors can be seen about a week on either side of this peak, as the shower ramps up to maximum and back down.
More meteors can be expected in the hours after midnight, when the Earth has us facing in the direction of the oncoming dust swarm. The two-day old crescent moon will set at about 9:20 p.m., leaving the sky nice and dark for the rest of the night — a perfect year for Perseid meteor watching.
Aug. 17: Venus at greatest eastern elongation
Sometime around the end of February, the planet Venus should peek out of the setting sun's glare and begin an eight-month gig as our dazzling Evening Star. The inferior planets, Mercury and Venus, spend much of their time too close to the sun for us to view well from planet Earth. They are the only planets that can pass both in front of the sun and behind the sun, as seen from Earth.
In between those passes by the sun, an inferior planet will swing out from one side of the sun to the other, during what are called its greatest elongations. It is during these greatest elongations that an inferior planet is best seen.
On Aug. 17, Venus will reach its greatest elongation 46 degrees on the eastern side of the sun and will dominate our western sky after sunset. Glowing as our Evening Star, Venus will outshine every other star-like object in the sky. Look for the slender crescent moon close to the Evening Star on these dates in 2018: Feb. 16, March 18, April 17, May 17, June 15, July 15, Aug. 14 and Sept. 12.
Venus will also pass close by several bright stars and star clusters this spring and summer. It will pass closest to the Pleiades star cluster April 24, bright star Aldebaran on May 1, star cluster M35 on May 20, the star Mebusta on May 27, the twin stars of Castor and Pollux on June 10, the Beehive star cluster on June 19, bright star Regulus on July 9, star Zavijava on Aug. 3 and bright star Spica on Aug. 31.
On March 18, Venus teams up with planet Mercury and the moon at dusk for a very unusual and beautiful conjunction. Look due west at 8 p.m. Near the time of elongation in mid-August, Venus will look like a tiny half-lit moon through any small telescope.
In the days that follow, Venus will start slipping closer to the sun again until it passes between the Earth and sun Oct. 26, an event called inferior conjunction. After that, Venus will swing out on the western side of the sun to shine as our Morning Star for the remainder of 2018.
Dec. 14: Geminid Meteor Shower
In spite of the cold December nights, the annual Geminid meteor shower is my favorite shower of the year. Their numbers equal or even surpass the August Perseids, and the bright stars of Orion form a wonderful backdrop.
No Geminid meteors were ever reported before the year 1862, but ever since, the shower seems to be increasing in strength every year. The source of the Geminid meteors was unknown until 1983, when the Infrared Astronomical Satellite (IRAS) found a small asteroid following the same orbital path as the meteor swarm. Named 3200 Phaethon, it is the only known asteroid that generates a meteor shower. All other meteor showers are associated with icy comets.
When Phaethon makes its close pass by the sun once every 1.4 years, the solar heat bakes and crumbles the asteroid's surface, leaving a trail of dusty debris in its wake. It is this dust swarm that the Earth moves through every December to create our Geminid meteor shower.
Under ideal dark sky conditions, a single observer can expect to see from 90 to 120 meteors per hour at the peak of activity. The meteors seem to shoot out of the sky near the twin stars of Castor and Pollux in the constellation of Gemini, hence the name of this shower.
This year, the six-day old moon will set before 11 p.m. on Dec. 13, leaving the after-midnight hours nice and dark for meteor watching. The peak of this year's shower is predicted for 5:30 a.m. Dec. 14, so the closer to dawn you are watching, the more Geminid meteors you are likely to observe.
But don't just watch on the night of the expected peak. Dozens of meteors can be seen for a night or two on either side of the peak.
Dec. 16: Comet Wirtanen brushes Earth
The performance of a comet is notoriously difficult to predict in advance, so I am going out on a limb a bit here with my final event of 2018. Comet Wirtanen, also called comet 46/P, is due to make a very close pass by the Earth in December and might — emphasis on might — become easily visible to the naked eye.
Comet Wirtanen was discovered in 1948 by Carl Wirtanen at the famous Lick Observatory in California. It follows a 5.4-year orbit around the sun, going from outside of Earth's orbit to inside of Jupiter's orbit. Close encounters with both planets over time keep the comet's orbit all stirred up and it never quite follows the same path twice.
On this pass, Comet Wirtanen will reach perihelion – its closest point to the sun – on Dec. 12, four days before its closest approach to Earth. On Dec. 16, the comet will pass only 0.0777 AU from Earth. That's equivalent to 7.1-million miles, or 32 times the distance from Earth to the moon, and puts Comet Wirtanen in the record books as the 10th closest comet to brush Earth since the year 1950, and 10th closest overall.
Because comets are basically dirty snowballs, they are most violently boiling away when they are closest to the sun. Comet Wirtanen's timing of closest approach to the sun and closest approach to Earth is ideal for creating the best show possible.
On the night of Dec. 16, there will be a bright waxing gibbous moon in the sky, but it will set by 2 a.m., leaving the comet in a nice, dark sky, positioned below the well-known Pleiades star cluster in the constellation of Taurus. Add to the mix that Comet Wirtanen is classified as a "hyperactive comet," and I think we have a really good shot at seeing a nice naked eye comet in our sky to close out the year 2018. Stay tuned for updates.
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Jimmy Westlake's "Celestial News" column appears monthly in the Steamboat Today. Check out Jimmy's new "2018 Cosmic Calendar" of sky events on his website at jwestlake.com. It features 12 of his best astro-photos and a day-by-day listing of cool celestial events that you and your family can enjoy watching all year.