Watch for Comet Encke’s fireball meteors

If you happen to be gazing toward the east on any of the clear, moonless (or nearly moonless) nights over the course of the next three months, you might notice a number of very bright meteors streaking across the sky.

The meteors, coming from the east, will be particularly visible if you are at a dark site away from city lights.

There are a number of meteor showers in the autumn months, and some — though not large in number — more than compensate with very bright fireball meteors.

Fireball meteors (not to be confused with bolides — meteors which, while also very bright, fragment when they enter the Earth's atmosphere) are meteors that reach a magnitude of -3 or brighter.

LOST AND FOUND COMET

Two of autumn's numerous meteor showers known for their fireballs are the South Taurids and the North Taurids. Both showers lie within the boundaries of the constellation of Taurus — the Bull and are associated with Comet 2P/encke.

This comet was discovered, lost and recovered a number of times throughout the late 18th and early 19th centuries. It was first discovered by French astronomer, Pierre Mechain, in January 1786, but because its orbit could not be confirmed and it was subsequently lost, it did not receive an official name. It was then re-discovered — and lost again — by German astronomer Caroline Herschel in November 1795, by French astronomer Jean Louis Pons in October 1805, and again by Pons in November 1818.

It wasn't until 1819 that the German astronomer,

J. F. Encke, recognized that the comets of 1786, 1795, 1805, and 1818 were, in fact, the same comet, which now bears his name. He successfully predicted its 1822 return.

The original debris stream from Comet Encke was, initially,

a single one. However, perturbations by Jupiter's gravity have, throughout time, split the original stream into two distinct branches — the South Taurids (generally seen between Sept. 10 and Nov. 20) and the North Taurids (normally Oct. 20 to Dec. 10).

Neither stream has a peak period (though some nights might have more Taurids than others, particularly when the two showers overlap), and usually average about five per hour. Both showers are known for their fireballs, very bright meteors lasting several seconds.

The radiant (apparent point of origin in the night sky) of the North Taurids lies between the Hyades star cluster (forming the head of the Bull) and

the Pleiades (The Seven Sisters) star cluster to the upper right of the Hyades. The South Taurids' radiant sits to the lower right of the North Taurid radiant. The Taurus constellation becomes visible above the eastern horizon by about 10 p.m. ADT (10:30 p.m. NDT) this month.

THIS WEEK’S SKY

Mercury and Mars are, once again, not visible in our night sky this coming week.

Venus (magnitude -4.3, look for it in Scorpius — the Scorpion) is visible around 6:55 p.m. ADT (7:35 p.m. NDT), nine degrees (about a hand's width at arm's length) above the southwest horizon, then dropping towards the

horizon, and setting by about 8:10 p.m. ADT (8:40 p.m. NDT).

Jupiter (magnitude -2.7, located in Capricornus — the Sea Goat) is likewise visible by 6:55 p.m. ADT (7:35 p.m. NDT), but in the southeast night sky, 19 degrees above the horizon, reaching 28 degrees above the southern horizon by 9:30 p.m. ADT (10 p.m. NDT), and remaining visible until about 1:30 a.m. ADT (2 a.m. NDT) when it drops below seven degrees above the southwest horizon.

Saturn (magnitude +0.5, in Capricornus) becomes visible by around 7:10 p.m. ADT (7:35 p.m. NDT) 21 degrees above the southern horizon, reaching a high point of 24 degrees above the horizon by

about 8:25 p.m. ADT (8:55 p.m. NDT), remaining visible until around 11:45 p.m. ADT (12:15 a.m. NDT) when it sinks below 10 degrees above the southwest horizon.

Watch the first quarter moon, then the waxing, gibbous moon, slide beneath Saturn and Jupiter on the evenings of Oct. 13 to 15.

Until next week, clear skies.

EVENTS

Oct. 13 — First-quarter moon

Glenn K. Roberts lives in Stratford, P.E.I., and has been an avid amateur astronomer since he was a small child. He welcomes comments from readers at glennkroberts@ gmail.com.

NASA This image, taken by NASA Spitzer Space Telescope, shows the comet Encke riding along its pebbly trail of debris along a diagonal line between the orbits of Mars and Jupiter.