April 2019

Welcome to SkyEye, your guide to this month's celestial events.

The Calendar

Look for red Mars as it traverses the constellation Taurus, passing two bright open clusters and the first-magnitude star Aldebaran.

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Date Body Event
1 Moon apogee
2 Mercury, Neptune conjunction: 0.4° apart
5 Moon new
10 Venus, Neptune conjunction: 0.3° apart
Mercury aphelion
Saturn west quadrature
2 Pallas opposition
Jupiter stationary point: direct → retrograde
11 Mercury greatest elongation west: 27.7°
12 Moon ascending node
Moon first quarter
13 Moon 0.2° south of the open star cluster M44 (known as Praesepe or the Beehive Cluster)
136199 Eris conjunction
16 136108 Haumea opposition
Moon perigee
Venus aphelion
18 Venus aphelion
19 Moon full
23 Earth Lyrid meteor shower
Uranus conjunction
Moon, Jupiter 1.6° apart
24 Earth π Puppid meteor shower
25 Moon, Saturn occultation of Saturn — visible from eastern Australia, New Zealand and the southern Pacific
Moon descending node
26 Moon last quarter
27 Saturn maximum declination north
28 Saturn minimum ring opening: 23.5°
Moon apogee
30 Saturn stationary point: direct → retrograde

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.

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Sun PiscesAries

Mercury AquariusPiscesCetusPisces

The southern hemisphere is the place to be in order to observe the dawn appulse of Mercury and Neptune on 2 April. The closest planet to the Sun reaches its second aphelion of the year on 10 April and then attains greatest elongation west the following day. At 27.7°, this is the largest elongation for Mercury in 2019.

Venus AquariusPiscesCetusPisces

Venus has dimmed to a still respectable magnitude −3.9 where it will remain for most of the rest of the year. Its phase is increasing (up to 88% by the end of the month) but it is getting ever more distant from Earth as it heads toward superior conjunction. The morning star is an impressive object when seen from tropical and southern latitudes where it rises more than two hours ahead of the Sun, but it remains fairly low in the east for northern hemisphere early risers. A telescope reveals Venus and Neptune to be only 0.3° apart on 10 April. Eight days later, Venus reaches aphelion.

Earth and Moon

Both the Lyrid and π Puppid meteor showers fall victim to the waning gibbous Moon.

Mars Taurus

Unlike many of the other outer planets, Mars is most favourably situated for northern hemisphere observation this month. It continues it journey past the sights of Taurus — M45 (the Pleiades), C41 (the Hyades), and bright Aldebaran — as it continues to dim (now magnitude +1.6) in the early evening sky.

Jupiter Ophiuchus

Jupiter continues to brighten as it approaches opposition in June and now shines at magnitude −2.3. The largest planet in the solar system remains near the horizon when viewed from northern temperate latitudes but is well aloft as observed from the tropics and the southern hemisphere. Jupiter reaches a stationary point on 10 April and goes into retrograde motion. On 23 April, the waning gibbous Moon passes less than 2° north of the planet.

Saturn Sagittarius

Quadrature is an interesting time to observe Saturn telescopically. The shadows of the planet, its rings and its bright satellites are cast noticeably to one side, leading to an eerie three-dimensional effect. West quadrature occurs on 10 April. Another lunar occultation takes place on 25 April when, beginning around 12:15 UT, the Moon eclipses the ringed planet. Retrograde motion commences on the last day of the month. Saturn is a morning sky object which is easiest to see from equatorial and southern latitudes.

Uranus Aries

Uranus is at conjunction on 23 April and is not visible.

Neptune Aquarius

A small telescope is necessary to view the most distant planet in the solar system but special care must be taken this month due to Neptune's proximity to the Sun following last month's conjunction. It is less than half a degree south of Mercury on the second day of the month and has an even closer encounter with bright Venus on 10 April. This blue ice giant now rises ahead of the Sun and is best viewed from southern latitudes.

The Celestial Sphere

Constellations are patterns of stars in the sky. The International Astronomical Union recognises 88 different constellations. The brightest stars as seen from the Earth are easy to spot but do you know their proper names? With a set of binoculars you can look for fainter objects such as nebulae and galaxies and star clusters or some of the closest stars to the Sun.

Descriptions of the sky for observers in both the northern and southern hemispheres are available for the following times this month. Subtract one hour from your local time if summer (daylight savings) time is in effect.

Local Time Mid-month Northern Hemisphere Equator Southern Hemisphere
1730 hours (1830 hours summer time) 60° N 50° N 40° N 30° N 20° N 10° N 10° S 20° S 30° S 40° S
1930 hours (2030 hours summer time) 60° N 50° N 40° N 30° N 20° N 10° N 10° S 20° S 30° S 40° S
2130 hours (2230 hours summer time) 60° N 50° N 40° N 30° N 20° N 10° N 10° S 20° S 30° S 40° S
2330 hours (0030 hours summer time) 60° N 50° N 40° N 30° N 20° N 10° N 10° S 20° S 30° S 40° S
0130 hours (0230 hours summer time) 60° N 50° N 40° N 30° N 20° N 10° N 10° S 20° S 30° S 40° S
0330 hours (0430 hours summer time) 60° N 50° N 40° N 30° N 20° N 10° N 10° S 20° S 30° S 40° S
0530 hours (0630 hours summer time) 60° N 50° N 40° N 30° N 20° N 10° N 10° S 20° S 30° S 40° S