A Show In the Sky All Year Round

Stanstead Journal - - NEWS - By Bruno Cas­tonguay

Shoot­ing stars can be one of the most en­ter­tain­ing shows pos­si­ble to see from your back­yard. Some peo­ple think they are rare but at some pe­ri­ods of the year me­teor show­ers can be very in­tense, with two hun­dred shoot­ing stars in one hour. On a per­fectly clear, dark sky, you can see dif­fer­ent types of them; some move slowly, oth­ers fast, some very bright, and some even leave a tale be­hind them like a plane. In fact, shoot­ing stars are me­te­oroids, small pieces of rock and ice with the av­er­age size of a pea. They en­ter our at­mos­phere at high ve­loc­ity, some­times thirty kilo­me­ters per sec­ond, and burn un­der the fric­tion of the air. When a big­ger one en­ters the at­mos­phere it gets bright enough to light up the whole sky and last many sec­onds; in science they are called “bolides.” Me­te­orites usu­ally dis­in­te­grate and never reach the ground, but de­pend­ing of the an­gle and speed they en­ter the at­mos­phere, some rare big ones strike the sur­face. Most shoot­ing stars fol­low the same direc­tion dur­ing a “me­teor shower” be­cause the Earth is pass­ing through a cloud of me­te­oroids. A me­teor shower can last mere min­utes or up to sev­eral weeks. But where are shoot­ing stars com­ing from? The an­swer is from comets. Comets fol­low cour­ses that range from the out­side edge of the so­lar sys­tem to the hot neigh­bor­hood of the sun. These cour­ses some­time cross the or­bit of the Earth leav­ing de­bris be­hind. The Earth passes through the same clouds at the same time ev­ery year, but the in­ten­sity of the show­ers vary as some comets can take many years to come back to leave more de­bris. So if comets are cross­ing the or­bit of the Earth why don’t they col­lide? To make a com­par­i­son, if the so­lar sys­tem is rep­re­sented by the size of Canada, the Earth is the size of a per­son, and a comet is the size of a mos­quito. The chance of get­ting bit­ten is nearly zero, even if at some point in their lives the per­son and the mos­quito visit the same camp­ground. The fol­low­ing im­age shows the phe­nom­e­non of comets, and me­te­orite clouds. I also in­clude a sched­ule of the most im­por­tant show­ers with the peak dates of each one. For this ce­les­tial event you don’t need an ex­pen­sive te­le­scope, all you have to do is lie back on a chair on a clear night and en­joy.

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