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 30° south. 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. Morning apparitions occur between inferior conjunction (when the planet is at its dimmest) and superior conjunction (when the planet is at its brightest) whereas evening apparitions always start bright and end with the planet around sixth magnitude. This year, Mercury appears at dawn three times and at dusk four.

Mercury's opening appearance in the morning (late January to the beginning of April, blue track) is the best opportunity for observers at latitude 30° S to catch a glimpse of this elusive planet, with Mercury reaching a height of 25.0° above the eastern horizon in the middle of February. The next morning apparition occurs from late May to mid-July (pink track) and affords planet watchers another chance to see the closest planet to the Sun. Its maximum altitude of 20.8° occurs in the first half of June. The final morning appearance between late September and early November is a poor one (green track), with Mercury not even reaching 9° above the eastern horizon.

Finishing up the final evening apparition of 2021, Mercury enters the year at an altitude of over 14° before descending towards the western horizon (blue track). The next appearance of Mercury at sunset occurs in April and May (pink track) and is the worst apparition for observers at this latitude, with the tiny planet only just cresting 10° above the horizon. This is followed by the best evening apparition (green track) which takes place between late July and late September. Mercury loops high into the sunset sky, reaching an altitude of 26.5° in late August. The closest planet to the Sun makes one final appearance in late November, peaking at a height of nearly 17° before finishing the year at around 10°.

Venus

Venus spends nearly the entire year as the morning star.

An excellent morning apparition of Venus greets early risers at latitude 30° south. The bright planet appears early in January and quickly vaults to a maximum height of 45.0° in the latter part of March. The morning star slowly declines in altitude until mid-June when the loss of height accelerates. Venus finally disappears from the dawn skies in early October.

The evening apparition of 2021 concludes in the first few days of 2022 (blue track) with Venus vanishing from the west during the first week of January. However, the evening star returns to the sunset sky at the end of October (pink track) and steadily climbs above the horizon through the end of the year, ending at an altitude of 13.5°.

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.