Brilliant Venus in west from dusk until early-to-mid evening. Venus – the brightest planet and third-brightest sky object overall (after the sun and moon) – presents its closest conjunction with the giant planet Jupiter for the year in late June and early July 2015. At their closest, Jupiter and Venus are about a moon diameter apart. Wow!
But don’t stop watching after July 1. There’s more. Venus will keep getting brighter and will display its greatest illuminated extent on July 9-10, around this time beaming at its greatest brilliancy as the evening “star.”
At mid-northern latitudes, Venus stays out for about two hours after sunset in early July, and sets about an hour after sunset by the month’s end; and at temperate latitudes in the Southern Hemisphere, Venus sets about three hours after sunset in early July, and about 1.5 hours after the sun by the month’s end. By mid-August, Venus will be gone from our evening sky. It will pass between us and the sun on August 15.
Throughout July 2015, brilliant Venus beams like a lighthouse at dusk and early evening! Be sure to catch the wonderful presence of the moon in Venus’ vicinity for several days, starting on July 17 or July 18.
Bright Jupiter from dusk until early-to-mid evening. Jupiter and Venus are spectacularly close in late June and early July, and they stay close as they fall nearer and nearer the sunset throughout July, 2015.
Jupiter shines more brilliantly than any star. It’s the second-brightest planet after Venus. In late June and early July, Venus and Jupiter stage their closest conjunction until August 27, 2016, but will again present a second – though less close – conjunction in the evening sky on July 31 – the same date as this year’s Blue Moon.
Venus and Jupiter shine fairly close together on the sky’s dome all through July 2015, and both Venus and Jupiter will transition over into the morning sky in August 2015.
After that, these two brilliant worlds will display their third and final conjunction of the year in the morning sky on October 26, 2015.
By a wonderful coincidence, on this same date – October 26, 2015 – Venus will reach its greatest eastern (morning) elongation from the sun, and the year’s closest grouping of three planets – Venus, Mars and Jupiter – will also take place on October 26. The next planetary trio won’t occur again until January, 2021!
If you have binoculars or a telescope, be sure to check out Jupiter’s four major moons, which look like pinpricks of light on or near the same plane. They are often called the Galilean moons to honor Galileo, who discovered these great Jovian moons in 1610. In their order from Jupiter, these moons are Io, Europa, Ganymede and Callisto.
These moons circle Jupiter around the Jovian equator. In cycles of six years, we view Jupiter’s equator edge-on. So, in 2015, we get to view a number of mutual events involving Jupiter’s moons through a high-powered telescope. Click here or here or here for more details.
Click here for a Jupiter’s moons almanac, courtesy of Sky & Telescope.
Saturn from nightfall until wee morning hours. Throughout July 2015, the golden planet Saturn transits – reaches its highest point in the sky – around sunset or dusk in the Northern Hemisphere and early evening in the Southern Hemisphere. Around the world, Saturn sets in the wee hours between midnight and dawn.
Binoculars don’t reveal Saturn’s gorgeous rings. For that, you need a small telescope.
Saturn’s rings are inclined at about 24o from edge-on in July 2015, exhibiting their northern face. A few years from now, in October 2017, the rings will open most widely, displaying a maximum inclination of 27o. As with so much in space (and on Earth), the appearance of Saturn’s rings from Earth is cyclical. In the year 2025, the rings will appear edge-on as seen from Earth. After that, we’ll begin to see the south side of Saturn’s rings, to increase to a maximum inclination of 27o by May 2032.
Mercury at dawn, in early July. Mercury is our solar system’s innermost planet and always stays near the sun in our sky. Mercury reached its greatest morning elongation from the sun on June 24, but this world might still be glimpsed before sunrise in the first week or two of July 2015. The Southern Hemisphere has the advantage. It will be a real challenge to catch the moon and Mercury in the morning sky on July 13 and 14.
Those at northerly latitudes aren’t quite as lucky this month. Morning dawn comes sooner before sunrise during our Northern Hemisphere summer than it does in the Southern Hemisphere (where it’s winter), so Mercury is more deeply buried in the glare of the morning twilight at northerly latitudes. Try scanning with binoculars.
At temperate latitudes in the Southern Hemisphere, this world actually rises before the onset of dawn from about June 14 to July 6, 2015. Look for Mercury over the sunrise point on the horizon as darkness first gives way to dawn. Click here to find out Mercury’s rising time in your sky, and for the time at which astronomical twilight begins.
Binoculars are always recommended to enhance sky views! Click here for recommended almanacs. They can help you know when Mercury rises in your sky.
Mercury will stay in the morning sky until July 23, 2015. Then it’ll pass into the evening sky, to give the Southern Hemisphere its most favorable apparition of Mercury for the year. Mercury will be in fine view for southerly latitudes from about mid-August to mid-September 2015. At northerly latitudes, this upcoming evening apparition of Mercury in August and September is about as unfavorable as it gets.
What do we mean by visible planet? By visible planet, we mean any solar system planet that is easily visible without an optical aid and that has been watched by our ancestors since time immemorial. In their outward order from the sun, the five visible planets are Mercury, Venus, Mars, Jupiter and Saturn. These planets are visible in our sky because their disks reflect sunlight, and these relatively nearby worlds tend to shine with a steadier light than the distant, twinkling stars. They tend to be bright! You can spot them, and come to know them as faithful friends, if you try.
Bottom line: Three of the five visible planets are visible in the evening sky throughout July 2015: Venus, Jupiter shine in the west first thing at dusk, and Saturn lords over the southern sky as darkness falls. The diligent observer might catch Mercury in the east before sunrise in the first half of July.