Event Date: February 9th
Time: 7:00 PM
Brief
The furthest outer planets, Uranus and Neptune, make their exits from our evening sky this month, with the former already out of view and the latter setting not long after Sunset. I showed them last month while Neptune was still barely visible and Uranus still decently high enough to see. As shown below however, our time with Uranus over the course of the next several weeks, is limited. The planet is already low enough once visible with optical aid, and having lost most of its blue-green color to atmospheric pollution. Take a look here, as it is still north enough of the Sun to see, yet setting four minutes earlier; the Sun is setting about a minute later each day this month on average, meaning that we will lose Uranus quickly.
Detailed
Besides showing Uranus and Neptune's positions relative to the horizon last month, I also showed their positions with star fields. Uranus, moves an average of about 4.3º each year, or about 7 years in each of the zodiacal constellations along the ecliptic. Therefore on average, disregarding retrogrades and changing rate in prograde, the Sun moves about 0.35º per month, which is the size of the field of view used to view Uranus at a decent magnitude. What am I getting to here? Simple. Each month, if using that aforementioned field, we see a new field of stars for Uranus. When near stationary, we see much less change in the field. Let's take a look now, using an even smaller field of a little more than 20', and see what type of pattern we have.
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click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.
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Okay, so you must be thinking, not much of a star field at all, correct?. That is fine, because normally when finding Uranus in the sky, I wouldn't use such a small field. Instead, we would use one closer to 1º to first find the planet, and zoom in later. In any case, here is Uranus to enjoy at about 200x, depending exactly what type of telescope you use.
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