SkyEye

What is an Apparition?

An apparition of a planet is the period during which it is visible, beginning and ending with solar conjunction. In the cases of the inferior planets Mercury and Venus, it is the time between inferior and superior conjunction (morning apparition) and the time between superior and inferior conjunction (evening apparition). Because inferior planets are always near the Sun, they only appear in the east before sunrise and the west after sunset.

Below are a series of diagrams showing the morning and evening apparitions of Mercury and Venus as observed from latitude 50° north. The planet is shown on the 1st, 6th, 11th, 16th, 21st and 26th days of each month with the current year's positions shown in bright white. The path may extend from the previous year or into the next.

Mercury

Mercury undergoes several morning and evening apparitions every year. This year finds Mercury in the morning skies four times and the evening skies thrice.

The final morning apparition of 2018 segues into the first morning apparition of 2019 (blue track). Mercury is already speeding back toward the southeastern horizon and soon vanishes. The next morning apparition (pink track) runs from March through May but is virtually unobservable from high northern latitudes. However, the morning apparition of July and August (green track) is much more favourable, with Mercury reaching an altitude of over 14° above the horizon. It is fairly bright, reaching zero magnitude at its highest point in the sky and continually brightening afterward. The last morning apparition (orange track) is even better. Mercury gets a little higher this time and is almost as bright.

First is best! The February–March evening apparition (blue track) rises to an altitude of nearly 16°. It begins at magnitude −1.5 and gradually fades to sixth magnitude by the middle of March. The next evening appearance of Mercury (pink track) begins in mid-May and lasts for two months. The tiny planet is brighter and it gets almost as high in the sky as it did in March. The final evening apparition (green track) skirts the horizon and is practically unobservable from this latitude.

Venus

Venus spends the first part of the year as the morning star, then switches to western skies in August.

This is a disappointing return to dawn skies for observers in northern temperate latitudes. Venus is already descending toward the horizon after reaching a maximum altitude of only 27° late last year and is never brighter than on the first of January.

Venus actually appears in the northwest before superior conjunction on 17 August but it stays low to the horizon until near the end of the year. Only then does it start to gain altitude. It is another disappointing apparition for planet watchers at this latitude but the view will improve next year as the evening star soars to an altitude of 41° in March 2020.

Sources

The dates, times and circumstances of all planetary and lunar phenomena were calculated from the JPL DE406 solar system ephemeris using the same rigorous methods that are employed in the compilation of publications such as The Astronomical Almanac.