What’s Up Above? March Stargazing

The night sky in March is different.  It’s a feeling type and visual type of difference. A celestial difference.  March is a month of transition for the night sky dome overhead. Enter the springtime sky. Most significant of this season is the vernal equinox, the transition from winter to summer, passing through spring.  Our Sun glides its ecliptic path noticeably higher in the daytime sky.  Days grow longer, and the nights feel not so cold.  (Dare I say this living in the mountains, where March is our snowiest month?)

The transition benefits the stargazer. We can now observe many of the outstanding gems of the winter sky without straining our necks to look straight up, and being outside at night is a bit less brutal.  Moreover, these spectacular winter jewels are viewable earlier in the evening. Unfortunately, for those of us living in the world of daylight savings time, once we “spring forward” evening now arrives later in the day. Is it a fair tradeoff? My hunch is you’ll answer “yes” after hearing what’s up above in March. This month there's the spring equinox, a full lunar eclipse, Saturn’s rings disappear from view (what?), and the winged god Mercury soars to great heights in the evening sky. That’s right, our innermost planet rises to the occasion giving us its best appearance of the year. Not bad, not bad at all. But first, the seasons go round and round.

The Vernal Equinox, March 20th 

We have four seasons on Earth; winter, spring, summer, and autumn. (Other planets have seasons, but that discussion is for another day.) Our seasons divide our journey around the Sun and are a result of our planet’s angle to the Sun. To complicate things, the season in the northern hemisphere is the opposite of the season in the southern hemisphere. It’s that darn Earth angle to the Sun thing again. The Vernal Equinox is the first equinox of the calendar year, and the astronomical beginning of the spring season in the northern hemisphere. This year, the equinox occurs at 3:01am local time. Oppositely, in the land down under and the southern hemisphere, it marks the beginning of autumn, the third equinox of the year. If you’re standing on the equator at the time of the spring equinox no matter where you are on Earth, the Sun will be directly overhead (assuming it happens in daylight hours) and day and night are approximately both 12-hours in duration. From this date forward the Earth tilts more towards the Sun in the northern hemisphere giving us more daylight hours, earlier dawns, and later sunsets.  Oh yeah!

A Conjunction of Jupiter, the Moon, and Pleiades (M45), March 6th

To begin, an astronomical conjunction is when two or more astronomical objects appear close to each other, to share the same spot in the night sky, so to speak.  It’s all about our point-of-view. To us, the objects share the same right ascension, or ecliptic longitude.  Basically, an “east-west” position in the sky.  While they appear to be up close and personal with one another, the distance between them in “depth” can be hundreds of millions of miles, or astronomical units; and in some instances a light year or two. This 6th of March you can see a delightful bright and unique mix of a moon, a planet, and an open star cluster. Plus, it’s easy to find, as the 6-day old waxing gibbous Moon directs you to Jupiter and the Pleiades, the Seven Daughters of Atlas, and Pleione to create an upside down scalene obtuse triangle. (Dig deep and get back to that high school geometry lesson for this one.)

About an hour after sunset, get outside and face the western horizon, and then look up to find the gibbous Moon.  Follow the path you just took up to the Moon, and now work back towards the same spot on the western horizon. The next big bright point of light to the right (west of the Moon) is Jupiter. Keep that distance as a reference. Now, continue following the same line down to the western horizon, and using the same Moon to Jupiter distance you’ll see a smug of light. Under clear skies it looks like a mini-big dipper. Seeing these three celestial objects within this intimate context, it is striking. Hope you get out and take a peek at this. Be under dark skies to fully appreciate this treat.

Mercury High and Bright, March 5th - 8th

The Winged Roman and Greek God of commerce, communication, and travel, and our teeny tiny innermost planet of our solar system, Mercury takes the celestial center stage on March 8th with two distinct astronomical events happening. First, Mercury achieves its greatest altitude in the evening western night sky, and just a touch past reaching its brightest magnitude in late February. Mercury achieves a dizzying (for Mercury) altitude at sunset of 16 degrees above the horizon. That’s high in the sky for that little guy. At the same time, Mercury’s -0.8 brightness, or magnitude makes it easy to find. That’s bright. 

To find Mercury this night look to the western horizon as the Sun sets, around 5:30pm. Find the planet Venus, which still dominates the western sky as the Sun crosses the horizon and twilight sets. Extend your arm, place a closed fist with your pinky finger on Venus. Move one fist width from Venus down and to the left (south). Mercury is bright enough for you to see it with your naked eye, but just barely. You are looking for a faint oyster pearl colored dot of light. You can distinguish it from the emerging background stars as it is a dot of light with a more defined edge, or limb. Mercury is swift, efficient; here and gone. You’ll have about 90-minutes to enjoy the view. Right now you can observe Mercury at its best. Get out and look. Don’t miss our cosmic messenger.

Total Lunar Eclipse, March 13th 

Get ready and take an afternoon nap to prepare yourself for a total lunar eclipse on the night of March 13th. We Earthlings are fortunate as the eclipse is visible from any location on Earth where the Full Moon is above the horizon at the time. This includes the Americas, Antarctica, Alaska, Africa, and north-eastern Russia. This month’s Full Moon is called the Worm Moon, and it is the first Full Moon of the spring season. Here’s a tidbit for you. For many years it was thought the Worm Moon referred to earthworms appearing in the soil. From worms to birds, spring begins to fill the air. Or, so it was thought. Recently it was discovered the moniker came from the Naudowessie indigenous people’s reference to the worms that emerged from tree bark as it thawed during early in the spring season.

More about this eclipse. An eclipse has distinct parts to it. Take a look at the image below. The eclipse begins when the Moon passes through an outer region of the Earth's shadow called the penumbra. As the outer part of the Earth's shadow, it appears to cover part of the Sun's disk, but not all of it as shown. Consequently the Moon's brightness will be reduced as it receives less light to reflect, yet the whole Full Moon's disk remains illuminated albeit dimmed and darker by a noticeable degree.

The penumbra eclipse begins at 9:58pm and continues to dim until it reaches its peak at 11:10pm and signals the start of the partial lunar eclipse as the Moon enters the Earth’s umbra. The Moon continues to move at 12:26am local time as the Moon is full within the Earth’s umbra and totality begins. The midpoint of the eclipse is at 12:59am, and the Moon begins to leave the Earth’s umbra at 1:31am. Around 2:48am the Moon is fully outside of the Earth’s umbra and the partial eclipse ends. The eclipse concludes when the Moon is fully outside of the Earth’s penumbra, close to 4am, on March 14th. 

Okay, I know it's late to be up and outside to observe an eclipse. I get it. Give it your best effort, however. Try to glimpse the start of the eclipse before you hit the hay. When you do, take notice how it is noticeably dimmer than a normal full Moon. I applaud your effort for doing so.   

Saturn Crosses the Line, March 23rd

The ringed planet, a gas giant, and the Roman god of agriculture, wealth, as well as the father of Jupiter, the king of the gods, grants us an special, rare and striking event this month. One never forgets their first view of the stunning rings of Saturn through a telescope’s eyepiece. So surprising that at first glance, Saturn’s ring system can create a sense of awe and wonder. It is an imprint in your memory that lasts a lifetime. The unique treat on the 23rd is called a “ring plane crossing.”  In brief, Saturn’s rings will appear to completely vanish because their thin edges will be aimed at Earth, so we’ll view the rings from an orientation called “edge on.”

The view is a consequence of orbital mechanics. You know those mechanisms which govern the path planets orbit around the Suns, and how moons orbit planets, and why satellites orbit Earth. These paths depend on factors like gravity, velocity, and orbital shape, together keeping objects traveling in predictable loops.

Saturn’s tilt along with orbit affects how we see its rings. As the planet continues on its journey around the Sun, our viewpoint of it changes. Saturn completes its orbit approximately 29.4 Earth years, and leans at an angle of 26.7 degrees. This means that from our point-of-view, Saturn toggles between the upper side of its rings when it’s tilted toward us and the lower side when it’s tilted away. When Earth transitions between each of these positions, it passes through Saturn’s “ring plane.” At that time our view of Saturn’s rings is in line with the edge of its rings, i.e., edge on, and the rings appear to vanish. Saturn will look like a pale yellow sphere through most telescopes as it moves through this transition. Through more powerful telescopes, a subtle line may be visible around the planet’s middle. 

The actual moment when the crossing of the plane occurs is 10:04am local time. If you desire to see Saturn closest to the moment of the crossing, it is that evening. Saturn is falling fast in the southwestern sky after sunset. Your best opportunity to see the vanishing rings that day is near 6:15pm local time. Take heart, the rings return to view in November of this year. In the meanwhile, grab your binoculars and take in this rare view of a ring-less Saturn. WARNING: Saturn will be close to the Sun at sunset. Look below (west) of the Sun to find Saturn. Exercise caution as the Sun will still be above the horizon. Never look directly at the Sun through binoculars or a telescope without proper protection.     

It’s time for stargazing. Sure, you still need to dress warm, wear a hat and gloves, and tolerate the cold, but all a little less so. Transition is in the air. The payoff is you can comfortably gaze at all of these celestial events. Can you do me a favor? Will you try and take in some of the total lunar eclipse this month? After you gaze upon the shifting phases of the eclipse look around and notice the other colorful jewels tossed haphazardly across our late winter night. You can’t help but notice Jupiter and Venus commanding the western horizon, and Mars, a red-hued orb almost directly overhead. Take it all in and feel just how expansive the universe is. Look around and inhale a March night sky.

Oh, and on the 20th, the spring equinox, if you’re so inclined go ahead and try to stand an egg on end. (It’s an old wives’ tale; that you can only do it on the equinox.) In truth, you can balance an egg on end any day of the year, if you’re patient. Have an egg-ceptionally happy spring.

Clear skies to you!