The brilliant Morning Star Venus continues to gleam from the eastern morning sky in early 2016. The chart above shows the rising of Venus, Mercury, Saturn, the star Antares and the moon compared to sunrise from January 14, 2016 through March 31, 2016. In addition Jupiter is shown setting in the west before sunrise. When Jupiter sets at sunrise in mid-March, it is opposite the sun, the astronomical event known as opposition. The interpretation of this chart is the topic of this article.
Important features above:
Before Astronomical Twilight (AT) the sky is as dark as it gets naturally. The sun is too far below the horizon to illuminate the sky or anything on the ground. AT is about 100 minutes long during the mornings shown the chart. During AT the sky begins to brighten to Nautical Twilight (NT), when the sky is bright enough to distinguish the horizon. The NT phenomenon is usually used by mariners to make measurements of celestial objects’ positions in the sky relative to the horizon for navigation purposes, occurring about 70 minutes before sunrise. The sky brightens further as the sun nears the horizon when objects on the ground are clearly distinguishable. During Civil Twilight (CT), Venus and the moon are visible, but other planets and stars are not seen. CT begins about 30 minutes before sunrise.
On the chart above, Venus rises before the beginning of AT until February 8. It is easily visible in the eastern sky throughout the time shown on the chart.
Mercury jumps into the morning sky, rising during CT until January 16. By January 22, it rises at NT. The planet does not rise before the beginning of AT during this appearance. The planet is very elusive, unless you know where to look for it. Another bright star, planet or the moon are helpful in locating Mercury; it rises before NT until mid-February.
Notice that on the chart, the Venus rising line and Mercury rising line do not cross. There is not a conjunction of the two planets where one passes the other. From late January through late February, Venus and Mercury appear near each other. Then Mercury rapidly disappears into bright twilight and into the sun’s glare.
The moon is displayed with a series of circles showing its rising time as calculated for Chicago, Illinois. Notice that the moon rises at about the same time as Venus on February 6 and March 7.
Five Planets in Sky
As Mercury moves into the sky, the five naked-eye planets are visible from east to west. Venus first catches our eye in the southeast. Dimmer, elusive Mercury is 7 degrees to the lower left of Venus; at chart time, Mercury is a week before its greatest separation from the sun. Saturn and the star Antares are higher in the south. Saturn is distinctly yellow-orange in color is Antares is a ruddy color. The color of the words “Saturn” and “Antares on the chart are indicative of their colors in the sky.
On the initial chart on this article, Saturn and Antares appear to rise at the same time. Antares is over 7 degrees from the planet and farther south. Antares is near the ecliptic, the imaginary line in the sky where the planets appear. With the planet-star separation, they can rise at the same time but be farther apart on the sky.
The moon is high in the south at chart time with reddish Mars 10 degrees to the lower left of the earth’s satellite. Jupiter is the bright star in the western sky. It is the brightest celestial sight in the western sky, yet over 4 times dimmer than Venus.
Venus and Mercury
As mentioned above, Venus and Mercury do not pass each other during this morning appearance of Mercury, but their rising times above indicate that they appear close together.
Here are important events to observe.
- January 31, 2016. As noted in the previous section, Mercury is over 7 degrees to the lower left of Venus.
- February 6, 2016. The crescent moon joins Mercury and Venus. Venus-Mercury = 5 degrees; Moon-Mercury = 3 degrees.
- February 12, 2016. Mercury and Venus are closest at 4 degrees separation.
- February 29, 2016. The planets are 7 degrees apart with Mercury rising just before the beginning of CT. What is the last day you can see Mercury without optical aid? What is the last day you can see Mercury through binoculars or a telescope?
- March 7, 2016: On its monthly passage through the firmament, the moon is near Venus again. The thin crescent moon rises at Nautical Twilight and Venus follows about 10 minutes later, about 50 minutes before sunrise. Find a clear horizon and look for them.
The first few months of the new year, provides an opportunity to see five planets in the morning sky and a long-lasting tandem of Venus and Mercury. Share your observations with us in the comments section.