SkyEye

The Calendar

Another penumbral lunar eclipse takes place this month, followed half a month later by an annular solar eclipse. Following inferior conjunction, Venus reappears in the east at dawn and is occulted by the Moon on 19 June.

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 Taurus → Gemini

Mercury Gemini

Mercury reaches a greatest elongation east of 23.6° on 4 June. This is the best evening apparition of the year for observers in northern temperate latitudes but it is also quite good for planet watchers in the southern hemisphere. This evening sky object spends the rest of June gradually sinking in the west and disappearing in sunset skies by the end of the month. Mercury reaches a stationary point on 17 June and enters retrograde motion. Six days later it goes through aphelion where it is at its most distant from the Sun. This tiny planet begins June at magnitude +0.3 but dims to sixth magnitude by the end of the month.

Venus Taurus

Venus undergoes inferior conjunction on 3 June and enters the dawn sky as the morning star where it will remain for the rest of 2020. Like the apparition which just finished, this appearance in the east before sunrise favours northern vantage points. The waning crescent Moon occults the waxing crescent Venus on 19 June in an event beginning around 06:45 UT and visible from northeastern North America. After spending six weeks in retrograde, Venus resumes direct motion on 24 June.

Earth and Moon

Another penumbral lunar eclipse takes place on 5 June, followed by a far more spectacular annular solar eclipse on 21 June. In between these two events, on 19 June, the waning crescent Moon blocks our view of Venus. Two meteor showers of note also take place this month. The Arietids are primarily a daytime shower and largely unaffected by moonlight but the June Boötids at the end of the month are not inconvenienced by the waxing crescent Moon.

Earth reaches solstice on 20 June. The word solstice means 'sun stands still' so that on this day, the solar declination reaches an extreme. In this case, the Sun appears directly over the Tropic of Cancer in the northern hemisphere.

Mars Aquarius → Pisces

Mars reaches west quadrature on 6 June. The red planet is around 1 au away from Earth at this time and shines at zero magnitude in the morning sky. When viewed through a telescope, it has a distinctly gibbous shape. One week later, the Last Quarter Moon passes 2.7° north of Mars. Just 14 hours later bright Mars and faint Neptune are even closer together. Mars is still primarily a morning sky object but for observers in the southern hemisphere, it rises before midnight.

Jupiter Sagittarius

The largest planet in the solar system rises during the early evening hours for astronomers in the southern hemisphere but those in northern temperate latitudes must wait until almost midnight for the brilliant object to appear in the east. The waning gibbous Moon glides past on 8 June, just over 2° south of Jupiter. The gas giant reaches opposition next month and at magnitude −2.6, is almost at maximum brilliancy.

Saturn Capricornus

The day after the waning gibbous Moon passes by Jupiter, it moves past Saturn, missing the planet by just under 3°. The ringed planet brightens from magnitude +0.5 to +0.3 this month as it moves closer to Earth and the rings open slightly. Saturn is found near Jupiter in the late evening and early morning skies.

Uranus Aries

Uranus is a morning sky object, shining dimly amongst the fainter stars of Aries.

Neptune Aquarius

Neptune attains west quadrature on 11 June and two days has an encounter with Mars when the two planets approach to 1.6° of each other. Ruddy Mars is easy to spot but a small telescope is necessary to view the most distant planet in the solar system. The blue ice giant reaches it most northerly declination for the year (−4.7°) on 19 June; four days later it reaches a stationary point and goes into retrograde.