As a planet moves across the sky there are particular points in its orbit that describe the motion, part of the jargon of astronomy that can confuse the uninitiated. These terms do not represent anything difficult, you just have to visualize what they mean. Understanding the movements of planets across the sky gives a little insight into our beautiful universe.
Elongation, opposition and conjunctions, the apparent positions of a planet with respect to the EarthThe terms used commonly here on Darker View are ideas that date back to the early beginnings of astronomy. Those ancient astronomers were fascinated by the movements of the bright wandering stars, the planets. They tracked and recorded the motions meticulously and invented the terminology we still use today to describe those motions.
Superior Conjunction, Inferior Conjunction, Opposition and Maximum Elongation tell any experienced skywatcher exactly where a planet is with respect to the Earth, where it is in our sky, and where it will be in the coming weeks or months. It is all part of the intricate patterns of our solar system that allow anyone who learns to become familiar with the night sky.
Venus will pass about one degree from Neptune on January 12th. The two will be quite close for several days, under 3°, from the 10th to the 15th, with close approach on the 12th. As the two are located high in the evening sky they are well placed for observation. This is an opportunity to find the distant ice giant with no difficulty at all. A telescope is required to see Neptune, at about 8th magnitude Neptune is about 60,000x dimmer than Venus shining at -4 magnitude. Check a chart for proper identification, there are several moderately bright stars in the region to confuse with the dim planet. On the 12th, a 6.9 mag star will directly between the two. The odd green-blue color of Neptune should help distinguish the planet.
Tonight a bright gibbous Moon will be just under 3° from the Pleiades star cluster. The Moon will be 84% illuminated, bright, but the cluster is bright enough to be seen even against a bright Moon. As the Pleiades move to the west over coming months there will be a few more lunar conjunctions, with increasingly smaller crescents.
Today the Earth is closest to the Sun, a point called perihelion. We will be about 147,098,290km (91,402,639miles) from the Sun. Compare this to the 152,098,232km (94,509,459miles) we will be at aphelion on July 4th, a difference of about 5,411,169km (3,362,344miles) occurs throughout one orbit.
It may seem odd that we are actually at the closest for the middle of northern winter, you just have to remember that proximity to the Sun is not the cause of the seasons. The seasons are caused by the axial tilt of the Earth, creating short and long days throughout the year, with a resulting change in the angle and intensity of the sunlight.
The first meteor shower of 2012 is likely to be a good one. The Quadrantids are a reliable shower, producing 60-120 ZHR, one to two meteors per minute. The Quadrantids are named for the obsolete constellation Quadrans Muralis, now part of the constellation Boötes.
For viewers in the mid-Pacific the peak will arrive early on the morning of January 4th. The radiant rises around 2am, creating a pre-dawn event. Set the alarm clocks early for this one. While the predicted peak is January 4, 07:20 UT (January 3, 21:20 HST) the show should be quite decent for hours either side of this time. Unlike other showers where activity can occur for days or even weeks, the Quadrantids have a sharp peak, activity falls off rapidly on the preceding and following nights.
The Moon is still a few days short of full, allowing several dark hours before dawn for meteor watching. Moonset will occur about the same time the radiant rises, about 2am, giving observers about three hours of good dark skies to enjoy the event.
Tonight the Moon and Jupiter will dominate the evening sky. They will be close to each other, about 9°40′ apart. The Moon will be a little over 60% illuminated, with Jupiter shining brightly at -2.6 magnitude. Tomorrow they will be even closer, at only 6° separation.
I did attempt to see comet C/2011 W3 Lovejoy in the daylight. I actually tried several times. Once on the morning of the 15th and a couple more times on the morning of the 16th after I heard that the comet had survived perihelion passage. Neither time did I see the comet with an unaided eye.
On the 15th I was not surprised I could not see it. I was in Waimea where there was a lot of low altitude haze and a lot of glare around the Sun. On the 16th I had a much better chance using the clean high altitude air of the summit of Mauna Kea. But still, no comet seen even though it should be just over four degrees from the Sun. This is about the same separation that had allowed me to see comet McNaught in early 2007.
Just to be certain I set the camera on a tripod, placed it just inside the shadow of the Keck 1 dome, and blazed away. Examining the photos on the camera display likewise revealed no trace of the comet, but there were some interesting spots of light.
It was not until I sat down and really analyzed the raw frames that I found something. Using some astronomy software, I calculated the position of the comet when the shots were taken and the field of view of the camera. And lo! There it was, a small spot with a trace of tail. It showed up best in the green channel, and not at all in the blue thanks to Rayleigh scattering in our atmosphere. Stacking nine of ten frames and processing the heck out of the frames does allow you to clearly see the comet…
Comet C/2011 W3 Lovejoy photographed 4° from the Sun on at 19:47UT on the morning of 16Dec2011. Canon 60D and an 85mm lens, stack of nine frames, green channel only.
