Friends, 2015 was a very interesting year for conjunctions of the Moon and planets. Long-time readers of this newsletter and other experienced sky observers understand that the classical planets are among the brightest objects in the sky, and are brighter that the actual fixed stars.
The planet Venus is blazingly bright, the third brightest object in the sky, exceeded in brightness only by the Sun and Moon, shining alternately as The Morning Star before dawn and The Evening Star after sunset.
The next brightest object in the sky is Jupiter, which is a bright blowtorch in the night sky. Jupiter is a superior planet, which can appear anywhere in the sky, unlike Venus, which is an inferior planet, and is only seen somewhere close to the Sun, usually in twilight.
Mars is usually modestly bright, not very conspicuous, dimmer than the brightest actual stars. Usually, Mars is only distinguished by its distinct rusty-red color. But every two years, as it draws close to the Earth at opposition, Mars blazes to a brightness that rivals Jupiter, and has the distinct copper color of a shiny, new penny.
Saturn is always fairly bright, comparable to the brightest actual stars. Unlike the other planets, Saturn does not move quickly against the background constellations, very slowly changing its position against the stars over a period of years.
Mercury is an inferior planet like Venus, always close to the Sun, seen alternately before dawn and after sunset. But Mercury never gets too high above the horizon in bright twilight, and is usually hard to see. Also, Mercury moves very quickly, and is not in the same place in the sky for more than a couple days. So Mercury is a rare and elusive sight.
The Moon circles around the entire sky every month, moving through the same constellations as the classical planets. So each and every month, the Moon passes by each of the planets, making its closest approach on certain nights of the month. These are lunar conjunctions, where the Moon and planets align in the sky.
There are also planetary conjunctions from time to time, when two or more planets lie along the same line of sight, as seen from the Earth, and appear close together in the sky. (Conjunctions of the Moon and planets are explained in detail in our Signs & Seasons curriculum.)
For whatever reason, our modern culture is unaware that the planets are the brightest objects in the sky after the Sun and Moon, and frequently align with the Moon and with each other. The planets were very famous sights in the sky since ancient times and throughout all history, and are mentioned in all literature prior to the 20th century. However, for reasons unknown, the planets are now forgotten in our generation today, and are unfamiliar to most average people in our modern world.
It would be great if this sad state of affairs could be rectified now, since 2016 will be a very rich year for conjunctions of the Moon and planets.
The fun begins in 2016 with the morning conjunction of the waning crescent Moon with the bright planet Venus this week, on the morning of Thursday, January 7, before sunrise. But as a special added bonus, Venus is currently lining up with the planet Saturn, which recently emerged from the sunrise, after being invisibly hidden on the opposite side of the Sun. This week, Venus and Saturn are very close together.
Saturn is very faint compared to Venus, and would not be very conspicuous in the morning twilight. But since Saturn will be close to brilliant Venus, it should be an easier sight to spot. Also look for the bright, first magnitude star Antares in the constellation Scorpius, which is also currently near Venus and Saturn. So this star will join the Moon and these two planets in the morning sky this week, and they will all be clustered together on Thursday morning.
Keep an eye on Saturn in the morning sky, and use it to help you learn the constellation Scorpius. Saturn will be passing through Scorpius in 2016, and will be seen there in the nights of spring and the evenings of summer, when some very interesting sights will be seen with this planet. So if you get acquainted with Saturn in Scorpius now, and start following it in the current season, you’ll be well-prepared for the planetary show to come!
The first big event in Saturn’s fun year will be a VERY CLOSE conjunction with Venus on the morning of Saturday, January 9. If you are able to spot these two planets when the Moon was nearby during the week, you should be able to spot them again on Saturday morning when they draw closest. Saturn is the little “speck” underneath bright Venus.
These two will be REALLY close, separated by only 0.09 degrees, less than one-third of a lunar diameter. If you saw the recent morning dance with Venus, Jupiter and Mars, then you’ll be interested to know that Venus and Saturn will be even closer on Saturday. This happens because these planets fall along the same line-of-sight as seen from Earth. Actually, Saturn is hundreds of millions of miles beyond Venus, on the far side of the Sun, while Venus is relatively close to the Sun. This close conjunction will especially favor western Europe, but it will still be close in the USA, and the east coast will be favored on this continent.
One interesting feature of this year is that Mars will line up closely with Saturn in the spring, and then these two planets will stay together throughout the summer, remaining within 10 degrees of each other. So when the Moon swings by each month, it align with both Mars and Saturn.
More interestingly, Mars will reach opposition on May 22 and Saturn will also reach opposition soon thereafter, on June 3. Mars will be as bright as Jupiter as both of these planets undergo their retrogradations together, at the same time, in the same part of the sky. With bright Antares nearby, this will present a conspicuous benchmark in the sky for observing the retrograde motions of these planets. We’ll explain more about all that in another newsletter in the spring.
Beyond that, the summer will be interesting as the entire solar system will be visible together in the evening sky! Saturn is currently within 90 degrees of Jupiter, so these slowest planets are now in the same quarter of the sky. All of the faster-moving inner planets will be passing between Saturn and Jupiter throughout 2016, offering numerous opportunities for observing lunar and planetary conjunctions.
The main event will be in August, 2016, which will be The Month of Evening Conjunctions! The Moon will pass by each of the visible planets over a succession of evenings, after sunset. This should be a very interesting month, in a season of reliably clear skies for most of us. But the whole month will climax during the last week of August, which will be The Week of Planetary Conjunctions! Mars will finally meet up with Saturn on August 25. These two will still be close together on August 27 when Mercury, Venus and Jupiter cluster up, with Venus and Jupiter being closely aligned, only 0.07 degrees apart, less than one-quarter of a Full Moon diameter!
The only problem is that these planets will be very close to the Sun at that time, and will be very low to the horizon after sunset. If you have access to a coastline, or very flat land in the Great Plains, you might be able to pick out these planets in bright twilight before they set.
As if all those conjunctions aren’t enough sky excitement for you all, there will be a series of monthly lunar occultations throughout 2016 between the Moon and the bright star Aldebaran in the constellation Taurus. Most of these events will not be visible from the USA or will only be visible in the daytime. But we will have a prime opportunity to see one in the early evening in the USA on the night of Tuesday, January 19, 2016.
Occultations are amazing events to observe. During an occultation, the Moon covers over Aldebaran and hides the star for a time. It’s fun to see before and after, when the star is extremely close to the Moon. The word “occultation” comes from the Latin word “to hide.” (And no, it has nothing to do with “the occult”!) An explanation is presented in Chapter 7 of our Signs & Seasons curriculum.
The times for viewing are tricky since occultations begin and end at different times in different locations, because of certain celestial factors. Here is a brief table of approximate times for several different USA locations, by no means claiming to be precise. It is strongly recommended that you go outside 10-15 minutes beforehand and enjoy the sight of Aldebaran as a little flea on the edge of the Moon. Aldebaran will disappear at the precise moment the occultation begins, and will not reappear for some portion of an hour:
Baltimore MD 9:28 PM EST
Boston MA 9:35 PM EST
Washington DC 9:28 PM EST
Washington DC 9:28 PM EST
Atlanta GA 9:22 PM EST
Cleveland OH 9:14 PM EST
Chicago IL 8:02 PM CST
Duluth MN 7:55 PM CST
Nashville TN 8:09 PM CST
Jackson MS 8:09 PM CST
Baton Rouge LA 8:16 PM CST
Fort Worth TX 7:46 PM CST
Seattle WA 6:22 PM PST
Los Angeles CA 6:03 PM PST
For precise local times for numerous locations in the USA, Canada and Europe, visit the IOTA website. This page includes a map showing visibility in the USA and Canada, and also includes a list of disappearance and reappearance times for many locations within the zone of visibility. However, it’s not very “user friendly” for astro-rookies, and you’ll have to hunt to find your location and info. Also, the times are given in UT (Universal Time). You will need to convert UT to your local time zone to find the times for your area, by subtracting the given time for the hour difference corresponding to your time zone, as follows:
EST = UT – 5 hrs
CST = UT – 6 hrs
MST = UT – 7 hrs
PST = UT – 8 hrs
CST = UT – 6 hrs
MST = UT – 7 hrs
PST = UT – 8 hrs
For example, the disappearance time for Cleveland, Ohio is given precisely as 2 14 36, which is 2:14 UT – 5 hrs = 9:14 PM EST.
Anyway, it’s pretty cool to watch these occultations, as the star completely winks out and vanishes at the precise moment of disappearance. Such a sight would be very cool as seen through a telescope, but please don’t run out and buy one just for that!
Also in 2016 is a transit of Mercury on the morning of May 9,when the black dot of the planet passes over the disc of the Sun. Mercury transits are not as large and conspicuous as transits of Venus, but they happen every few years, unlike Venus transits, which occur in pairs every 130 years. This event is definitely for a filtered telescope, and you might be able to find a planetarium or observatory in your area setting up a scope for viewing.