SkyEye

The Calendar

Once again the Sun is partially eclipsed by the Moon, this time on 11 August. Since solar eclipses occur when the Moon is new, dark skies will accompany the famous Perseid meteor shower which peaks the following day. Finally, Comet C/2017 S3 (PanSTARRS) may brighten to naked-eye visibility this month as it reaches perihelion on 15 August.

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 Cancer → Leo

Mercury Leo → Cancer → Leo

At inferior conjunction on 9 August, the closest planet to the Sun doesn't reappear in the morning sky until past mid-month. It stays close to the horizion for those observing it from the southern hemisphere but it jumps much higher in the twilight for viewers in the northern hemisphere, descending only slightly after greatest elongation west on 26 August. Mercury reaches a stationary point on 18 August, changing from retrograde to direct motion.

Venus Leo → Virgo

The evening star appears twice as high above the western horizon when viewed from the southern hemisphere as from the north. It reaches greatest elongation east on 17 August.

Earth and Moon

The waning crescent Moon totally eclipses the star Aldebaran on 6 August and the New Moon partially eclipses the Sun on 11 August. The next day, dark skies greet this year's Perseid meteor shower. Peak activity may occur anytime between 20:00 UT on 12 August and 8:00 UT on 13 August.

Mars Capricornus → Sagittarius → Capricornus

Mars is getting easier to spot from northern latitudes, blazing away at magnitude −2.5 in the skies around midnight. It reaches a stationary point on 28 August when it changes from retrograde to direct motion across the sky.

Jupiter Libra

Best seen from southern latitudes, Jupiter reaches quadrature on 6 August. This is a particularly interesting time to observe the planet and its larger moons through a telescope as the shadows are noticably cast to one side.

Saturn Sagittarius

The ringed planet is an evening sky object and best viewed from southern vantage points.

Uranus Aries

It seems that most of the superior planets are best viewed from the southern hemisphere and that includes Uranus. From favoured positions, the green planet rises around midnight. On 7 August, Uranus reverses direction and begins retrograde motion.

Neptune Aquarius

A small telescope is necessary to view the most distant planet in the solar system and this is the best time to look because Neptune is at opposition early next month, meaning it's at its closest and brightest.