SkyEye

The Calendar

Venus has a busy month, passing close by Praesepe, Mars and Regulus in the space of three weeks. Earth reaches aphelion on 5 July and at the end of the month, the Southern δ Aquariid meteor shower is lost to moonlight.

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 Gemini → Cancer

Mercury Taurus → Orion → Gemini → Cancer

Mercury is visible in eastern skies before dawn. It reaches its greatest elongation west of the Sun (21.6°) on the fourth day of the month. At this point it begins to descend back toward the horizon as seen from the southern hemisphere but observers in northern temperate latitudes will see the bright planet continue to gain altitude for a few more days before it heads downward. Beginning July at a brightness of +1.0, it brightens over two magnitudes during the month. Another perihelion (the third this year) occurs on 24 July. Look for Mercury early in July before it gets too low to the horizon.

Venus Cancer → Leo

On the third day of the month, southern hemisphere observers will have the best opportunity to see Venus come within 0.1° of the open star cluster Praesepe or M44. The evening star is half a degree north of Mars just ten days later but Venus is five magnitudes brighter than the red planet. Venus also outshines Regulus when the two come close together on 21 July. Venus remains close to the western horizon for astronomers in northern temperate latitudes and the long twilight of summer may make observing the evening star problematical.

Earth and Moon

Earth reaches aphelion, the point in its orbit when it's farthest from the Sun, on 5 July. The major meteor shower of the month, the Southern δ Aquariids, is obliterated by the light of the waxing gibbous Moon near the end of July.

Mars Cancer → Leo

Like Earth, Mars reaches aphelion this month with the red planet farthest from the Sun on 13 July. Coincidentally, it is only half a degree from Venus on the same day. Mars passes first-magnitude star Regulus on 29 July. The second-magnitude planet is visible in the west after sunset but is getting increasingly difficult to see from northern latitudes. Southern hemisphere observers may have a slightly easier time spotting the planet.

Jupiter Aquarius

Jupiter reaches opposition next month so its rising time is getting ever closer to sunset. The gas giant appears in the east in the early evening hours and is best viewed from the southern hemisphere where winter skies darken early.

Saturn Capricornus

Saturn is rising ever earlier in the evening ahead of next month's opposition. Although best observed from southern latitudes, northern planet watchers are finally getting a look at the ringed planet as it rises during the evening twilight. Saturn's magnitude increases from +0.4 to +0.2 at the end of the month.

Uranus Aries

Best viewed from the southern hemisphere where sunrise comes late, Uranus is a morning sky object, rising around midnight. The waning crescent Moon passes 1.9° south of the faint planet on 4 July.

Neptune Aquarius

A small telescope is necessary to view the most distant planet in the solar system. Northern hemisphere observers are finally seeing Neptune rise before midnight but the best views of this elusive object are from southern latitudes on those nights when the Moon is absent from the sky.