SkyEye

The Calendar

Observers in northern temperate latitudes get their best evening views of Mercury this month and next. The Last Quarter Moon does no favours for the Lyrids and π Puppids later in April but Earth is treated to a partial solar eclipse on 30 April when the second New Moon of the month occults the Sun.

The Solar System

The word planet is derived from the Greek word for 'wanderer'. Unlike the background stars, planets seem to move around the sky, keeping mostly to a narrow track called the ecliptic, the path of the Sun across the stars. Dwarf planets and small solar-system bodies, including comets, are not so constrained, often moving far above or below the ecliptic.

Sun Pisces → Aries

Mercury Cetus → Pisces → Aries → Taurus

Following superior conjunction on the second, Mercury returns to the west after sunset in what is the best evening apparition of the year for observers in northern temperate latitudes. As it ascends into the early evening sky, it undergoes its second perihelion of the year on 13 April and visits Uranus five days later. (Mercury passed the other three gas giants last month.) Greatest elongation east takes place on 29 April, the same day it passes 1.3° south of the Pleaides.

Venus Capricornus → Aquarius → Pisces

Venus passes through its descending node on 10 April, moving from north of the ecliptic to south. The morning star encounters two superior planets in the dawn sky, Neptune on 27 April and Jupiter on the last day of the month. The two bright planets will be only 0.2° apart on 30 April. Venus and its close encounters with the gas giants are best viewed from the southern hemisphere where the morning star is quite high above the horizon before sunrise.

Earth and Moon

The very young Moon occults Uranus on the third day of the month. Later in April, the two meteor showers this month, the Lyrids and the π Puppids, are marginally inconvenienced by the Last Quarter Moon. The second New Moon in April participates in a partial solar eclipse at the very end of the month.

Mars Capricornus → Aquarius

The red planet glides past the ringed planet on 5 April. The two objects are of a similar brightness but Mars takes on a redder hue. Both planets are visible in the morning sky, rising hours before dawn from southern vantage points but mired in the brightening sky when viewed from northern temperate latitudes.

Jupiter Aquarius → Pisces

On 12 April, Jupiter and Neptune participate in a conjunction, the first one since their triple conjunction in 2009. This event won't happen again until 2035. A far more common planetary conjunction occurs at the end of the month with the morning star. Jupiter is still mired in dawn twilight for northern temperate observers but southern regions have good views of the gas giant in the dark early morning skies.

Saturn Capricornus

Mars moves past the ringed planet on 5 April, approaching to around 0.3°. Saturn is visible in the morning and is best seen from southern latitudes where it rises around midnight. Observers farther north will find Capricornus low to the horizon, making the planet difficult to see clearly.

Uranus Aries

Uranus is lost in the evening twilight, necessitating optical aids to spot it before it sets not long after the Sun. The Moon is only two days past new when it occults Uranus on 3 April, an event just barely visible from the African nations of Sierra Leone, Liberia, Côte d'Ivoire and Ghana beginning around 19:00 UT. Conjunction is imminent and Uranus is lost to view late in the month.

Neptune Aquarius

A small telescope is necessary to view the most distant planet in the solar system. Now a morning sky object following last month's conjunction, the faint planet is best viewed from the southern hemisphere where it quickly distances itself from the Sun. For observers in northern temperate latitudes, Neptune rises during twilight. Two planets, Jupiter and Venus, pass by the blue ice giant on 12 April and 27 April respectively. This is the first time since 2009 that Jupiter and Neptune have met in the sky.