This Week: Neptune Opposition 2018 and Comet 21P!

Neptune image by Voyager 2 probe. NASA/JPL

With the moon a waning crescent, it is a good time to pick out some faint objects in the sky.

On Friday, September 7th, Neptune rises opposite the sun and is closest to earth. Being in the sky all-night, and at it’s brightest, presents a good opportunity to sight this rarely-seen telescopic planet. Unlike the naked eye planets, you’ll have to crank-up the power to make sure you’ve really found it. Even at 100x it just looks like a magnitude 7.8 star. So don’t expect to see a Voyager 2 quality image through your eyepiece.

Click on image to enlarge. Neptune (dots showing position from Sept. 5 to 12) is just south of a line between Phi- and Lambda-Aquarii. In early September it will be moving slowly toward the Lambda star. Using your finder, or a wide-field eyepiece, setup your field on the stars labeled by magnitude inside the 5° circle. Over the course of the week, Neptune will be approaching a line drawn between the mag. 7.5 and 7.4 stars shown. Neptune will be slightly dimmer than both at mag. 7.8.  83-Aquarii it is the brightest of the stars labeled by magnitude — shining at  mag. 5.5 — and will help you orient the chart.

Continue reading “This Week: Neptune Opposition 2018 and Comet 21P!”