The Gem­i­nid Me­teor Shower: An early hol­i­day treat for stargaz­ers

Woonsocket Call - - BLACKSTONE VALLEY - By DAVID A. HUESTIS

As the year ad­vances into the month of De­cem­ber, sun­rise times oc­cur much later in the morn­ing, while sun­set times oc­cur much ear­lier. Here in south­ern New Eng­land the lat­est sun­rise is around 7:13:09 a.m. on Jan. 2, whereas the ear­li­est sun­set is around 4:14:58 p.m. on Dec. 11. De­spite the usu­ally in­creas­ingly cold nights, am­a­teur as­tronomers are able to be­gin their ob­serv­ing ses­sions soon af­ter the din­ner hour. There­fore, De­cem­ber is wel­comed by many stargaz­ers since it of­fers many hours of dark skies... as long as a bright Moon does not in­ter­vene.

Dur­ing mid-to-late Novem­ber, for those of you who com­muted to work in an east­erly di­rec­tion had surely no­ticed a bril­liant bea­con above the east-south­east hori­zon be­fore sun­rise. That daz­zling ob­ject was the planet Venus. Venus will con­tinue to dom­i­nate the morn­ing sky as De­cem­ber be­gins. A beau­ti­ful sky scene will greet your eyes on the morn­ing of the third as a wan­ing cres­cent Moon will ap­pear about six de­grees above our plan­e­tary neigh­bor.

Join­ing Venus dur­ing early De­cem­ber will be our so­lar sys­tem’s clos­est planet to the Sun – Mer­cury. Mer­cury will con­tinue to as­cend into the sky un­til the 10th af­ter which it will then be­gin to de­scend back to­wards the hori­zon and the Sun. Around this time, de­pend­ing upon your view of the hori­zon, you may be­gin to see the re­turn of Jupiter. Each morn­ing Jupiter will rise higher into the sky as Mer­cury is set­ting. On the 22nd these two worlds will ap­pear within one de­gree (two full Moon di­am­e­ters) of each other. So if you’ve never ob­served Mer­cury try us­ing Jupiter as your guide to do so. By month’s end Mer­cury will dis­ap­pear from view in bright morn­ing twi­light.

While Mars con­tin­ues to be vis­i­ble through­out De­cem­ber, the dis­tance be­tween our two worlds in­creases from 94,469,737 miles to 117,172,414 miles by month’s end. That means the im­age size of the planet through a tele­scope will con­tinue to shrink. I sus­pect Mars’ sur­face de­tail will be dif­fi­cult to dis­cern in smaller in­stru­ments. Con­sider how much the Earth has pulled out ahead of Mars in our re­spec­tive or­bits. Back at clos­est ap­proach at the end of July the Earth and Mars were a mere 35,785,537 mil­lion miles apart.

I al­ways look for­ward to the north­ern hemi­spheres’ best shoot­ing star dis­play – the Gem­i­nids. With the peak of me­teor ac­tiv­ity on the night of Dec. 13-14, I re­gard this show­ers’ ap­pear­ance as an early hol­i­day gift from the Uni­verse. And for 2018 if weather con­di­tions are fa­vor­able about 60plus me­te­ors per hour may be seen from about 10 p.m. once the wax­ing cres­cent Moon sets un­til the sky be­gins to brighten dur­ing dawn. With no in­ter­fer­ing moon­light stargaz­ers will have an op­por­tu­nity to see as many me­te­ors as pos­si­ble. All you will need is a dark-sky lo­ca­tion devoid of in­ter­fer­ing light pol­lu­tion sources.

An ob­server can usu­ally count on the tem­per­a­ture to be at or be­low the freez­ing mark dur­ing the Gem­i­nids. Re­gard­less, I still rec­om­mend sit­ting or re­clin­ing in a com­fort­able lounge chair. Dress in lay­ers. Climb into a sleep­ing bag if pos­si­ble. Wear a hat to keep heat from es­cap­ing through your ex­posed head. Wear warm mit­tens, not gloves. Mit­tens keep your fin­gers to­gether for added warmth. You can also use a few of those pocket warm­ers to keep ex­trem­i­ties toasty.

Keep warm and alert, but don’t get too comfy out there. I’ve told the fol­low­ing story many times since it oc­curred, but it is a cau­tion­ary tale that bears re­peat­ing.

Many moons ago dur­ing a Gem­i­nid me­teor shower watch from Sea­grave Ob­ser­va­tory, the sky was clear when we started ob­serv­ing. How­ever, some­time dur­ing the night we all fell asleep. When we awoke we re­al­ized some clouds had paid us a visit, since we were all cov­ered with a dust­ing of snow. Moral of that story is… stay awake while me­teor ob­serv­ing dur­ing the win­ter. Oth­er­wise they may have to pick you up with ice tongs and thaw you out in the morn­ing.

One im­por­tant fact to re­mem­ber if you can­not ob­serve the Gem­i­nids through­out the night un­til dawn is that this shower is one that can be ob­served be­fore mid­night. You won’t see the peak rate of me­te­ors, but you will see more than you could on any ran­dom night of sky watch­ing. And there can be one ad­van­tage if you ob­serve within a few hours of sun­set. You may catch a few Gem­i­nid earth graz­ers as they skim tan­gen­tially across the top of Earth’s at­mos­phere and par­al­lel to the hori­zon. This sce­nario pro­vides for much longer streaks, of­ten look­ing like a stone skip­ping across a pond.

While the Gem­i­nids ap­pear to ra­di­ate from Gemini near its bright­est stars, Cas­tor and Pol­lux, scan around the sky as much as pos­si­ble. As the night pro­gresses and Gemini moves across the sky to­wards the west, your scan should move as well. At around 2:30 a.m. Gemini will be on your north/ south merid­ian, just south of zenith. The num­ber of me­te­ors per hour should in­crease through­out your ob­serv­ing ses­sion. You’ll know you’ve seen a Gem­i­nid if you can trace the ori­gin of the me­teor’s trail back to the ra­di­ant point.

The Gem­i­nids are fairly bright and mod­er­ate in speed, hit­ting our at­mos­phere at 21.75 miles per se­cond.

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