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 both in the morning and evening skies four times.

The final morning apparition of 2019 finishes in the beginning of the year (blue track) but Mercury is already too close to the horizon to spot. The next appearance (February–April, pink track) is particularly poor, with the planet not even making 7° in altitude. Fortunately, the summer apparition (green track) in July and August is much better, with a brightening Mercury appearing nearly 13° above the eastern horizon. However, it is the final apparition of the year (orange track) which is the best for observers at this latitude, with Mercury rising nearly 16° in altitude around the time of greatest elongation west and reaching magnitude −1.0 before vanishing below the horizon.

Mercury's first evening apparition of 2020 (blue track) is a good one, with the planet reaching 15° in altitude. It is best to catch a glimpse in January, though, because the planet is dimming as it heads to inferior conjunction in late February. The next appearance of Mercury in the evening skies occurs in May and June (pink track). This is the best evening apparition for observers at 50° north latitude, with the elusive planet gaining 16° altitude above the northwestern horizon. However, as is always the case with evening apparitions of Mercury, it is best viewed early (May in this instance) as it is losing brightness with every passing day. It is zero magnitude at around greatest elongation but only fourth magnitude by the end of the apparition. The August–October apparition (green track) is virtually unviewable, with Mercury no higher than 4.6° above the horizon. The final apparition (orange track) is just getting underway when the year ends and the planet is too close to the horizon to be easily visible.

Venus

Venus spends the first part of the year as the evening star, then switches to dawn skies in early June.

Venus appears as the morning star for the last half of 2020 and gives a much better showing than last year. Rapidly climbing away from the Sun in June, Venus attains over 36° in altitude in September before heading back toward the eastern horizon. It finishes the year at an altitude of 10° in the southeast. Venus is brightest near the beginning of this apparition but is still a respectable magnitude −3.9 in December.

The evening star is already nearly 20° above the southwestern horizon when 2020 begins. Venus continues to climb away from the Sun, reaching an altitude of 41° in late March and brightening to magnitude −4.5 in April and May. However, inferior conjunction in June beckons and Venus's position above the horizon rapidly declines in May before it disappears at the beginning of June.

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.