In April of 1997 I was with a friend in Washington, D.C., visiting the National Air and Space Museum.
That evening we took the Metro (underground railway) back to our hotel. As we walked up the stairs to the street, my friend asked me where the famous comet of the century (Hale-Bopp) was in the night sky. I told him that it was near the Big Dipper but in downtown Washington, D.C., the light pollution wouldn't allow us to see it.
But as soon as we walked outside, there it was - including its characteristic sweeping tail!
After viewing the newest comet to brighten Earth's night sky, NEOWISE, it reminded me of Hale-Bopp. Although not as bright, NEOWISE is every bit as large and beautiful.
Like Hale-Bopp, NEOWISE is a long period comet, meaning it takes a long time to complete one orbit around the sun. Latest estimates are that NEOWISE will take another 6,800 years to return again to grace our night sky.
Earth tracks a relatively circular orbit around the sun each year. However, NEOWISE's orbit resembles a stretched rubber band reaching way out into the realm of the Kuiper Belt far beyond Pluto. The sun acts as an anchor point for the end of its elongated orbit that takes it closest to Earth.
It's likely that eons ago a passing star perturbed the orbit of NEOWISE to make it "fall" toward the sun. Comets with super stretched orbits like NEOWISE are in danger of breaking up due to how close they come to the sun before sling-shotting out again to the ultra cold outskirts of our solar system.
These comets are called "sun grazers" because their perihelions take them so close that sometimes the sun's deep gravity literally sucks them into itself. NEOWISE is lucky to have avoided this fate perhaps because it has an internal structure that is more dense than the loose and diffuse "dirty snowball" makeup of most comets.
NEOWISE will be visible (about an hour after sunset) skirting along and near the bottom of the bowl of the Big Dipper and continuing past the Big Dipper's handle toward the constellation Bootes for the rest of July. It made its closest approach to Earth on July 22, when it was a magnitude 4 and visible to the naked eye although binoculars were needed to see it in all its splendor.
By the end of the month, NEOWISE will be five times dimmer than it was at closest approach but still visible through binoculars or a small telescope. This 3-mile diameter ice and snowball is sporting such a long tail (about four moon diameters) that wide field optics including DSLR cameras on tripods (up to 10 second exposures) are the best ways to view it.
Astronomical calendar for August
Aug. 1 (Saturday): Jupiter 1.5 degrees above the moon. Look above the southeast horizon to see Jupiter act as a top hat for the moon.
Aug. 2 (Sunday): Saturn takes over to act as a full-brim straw hat atop the moon tipped slightly to the right of our lunar neighbor.
Aug. 3 (Monday): Full Sturgeon Moon.
Aug. 8 (Saturday): Red-orange-hued Mars takes its turn topping the moon like a jaunty hat tilted to the moon's left side. You'll have to wait until after 11 p.m. to see it because of a late moonrise.
Aug. 11 (Tuesday): Perseid meteor shower. The peak of this shower will occur at 7 a.m. the next morning (Aug. 12). The sun will blot out even the brightest meteors at that time so plan on lying down on a lounge chair or blanket in an open field at a dark sky site to count as many as 40 meteors per hour from 10:30 p.m. on Aug. 11 to 100 meteors per hour in the predawn sky (3-4 a.m. Aug. 12).
Even though all Perseids will appear to come from one spot, look all over the sky to see these white to bright green streaks of light sometimes with glowing smoke trails. This, in my opinion is the best most reliable meteor shower of the year. The moon won't spoil the view until after midnight. Dress warmly and enjoy!
Aug. 12 (Wednesday): Venus highest in the predawn sky. Brilliant Venus will outshine even commercial jets with their landing lights on from 4 to 5 a.m. above the east-northeast horizon.
Aug. 22 (Saturday): Double moon shadow transit across Jupiter. If you can plan ahead to stay awake until after midnight, you'll be in for quite a treat. Train a small telescope equipped with a medium- to high-power eyepiece on Jupiter at 12:32 a.m. Saturday morning to see the Great Red Spot on one side followed by shadows of the moon Ganymede on the other side of the Jovian planet.
Gary Zientara owns Mount Sangre Observatory in Angel Fire.