During the final days of June and the first days of July we have the most striking naked-eye planetary sight of the year.
You may have already noticed Venus and Jupiter as brilliant lights in the west on June evenings. You may have also noticed that, night by June night, Venus and Jupiter have appeared to get closer to each other. This will culminate in a gathering of Venus and Jupiter on Tuesday evening, when the two planets will appear extremely close to each other. They will be separated by a mere third of a degree, which is less than the width of the full moon.
Since this article appears on the Sunday before the event, I will start with Sunday, June 28, and take it into July. During these days, look west about 30 minutes after sunset, or around 7:40 p.m. Venus and Jupiter will be about a third of the way up in the west. During this key week of their conjunction, the two planets emerge from the dusk around 7:40 p.m. and set in the west at 9:45 p.m. Venus shines at blazing minus 4.6 magnitude, and Jupiter at minus 1.8.
» On Sunday, brighter Venus will be about 1 degree below Jupiter. One degree is about twice the diameter of a full moon, or the thickness of your pinky finger held at arm’s length.
» On Monday, Venus will still be below Jupiter but will have moved visibly closer to Jupiter in the sky; Venus will be half a degree below Jupiter, or the width of a full moon.
» On Tuesday, the night of the closest apparent approach of these two planets, Venus will be only a third of a degree from Jupiter, and will appear down and to the left of Jupiter.
On Wednesday night, the two planets will be side by side, with brighter Venus being about half a degree to the left of Jupiter. From Thursday onward, Venus will be above Jupiter, to its left, and getting a little further from Jupiter each night. By July 10, Venus will be 4 degrees (the thickness of two of your fingers at arm’s length) to the upper left of Jupiter.
As the month goes on the two planets will set a little earlier each night as well; while they set at 9:45 p.m. at the start of July, Jupiter and Venus hit the western horizon at 9:30 p.m. by July 9. On that night, by the way, Venus will hit its brightness peak, shining at minus 4.7 magnitude.
On July 18, there is a beautiful grouping of these two planets and the moon. Look for the crescent moon to the left of Venus on that evening. By then, Venus will be 6 degrees to the left of Jupiter (three fingers’ thickness) and still slightly higher than Jupiter.
Toward the end of the month, Venus and Jupiter will be a little lower in the sky at dusk and will set a little earlier. By July 26, Venus will again be side by side with Jupiter and to its left; the two dots still emerge from the twilight around 7:45 p.m., but set at 8:30 p.m., an hour earlier than they set at the start of July.
After a spectacular June and July, we lose both Venus and Jupiter in early August; by Aug. 3, Venus is lost in the sun at dusk, and Jupiter is lost in the sun by Aug. 10.
Other July planets
Saturn is also visible all of July in the early evening sky. In early July, Saturn appears halfway up in the southeast at dusk, is due south at 10 p.m., and sets in the west-southwest at 3:15 a.m.
By the end of the month, Saturn is due south at dusk and spends the night working its way down the western sky, setting in the west at 1:15 a.m. Saturn is currently to the right of the claw of Scorpius. As shown on our July star map, this famous constellation has four stars that mark off the claw of the scorpion (or the top of the fishhook if you see it as Maui’s Fishhook). In July, Saturn appears as a whitish-yellow dot in front of the bluish-white stars of the actual claw stars.
Mercury rises in the east-northeast just before dawn in the first week of July, but the time slot to see Mercury is narrow; it rises at 4:30 a.m. and is lost in the breaking day at 5 a.m. Mercury gains in brightness, reaching minus 1 by July 10.
Other sky events
» There are two full moons in July, on the first and the last days of the month. The second full moon in a month is called the "blue moon" and the July 31 blue moon is the first since August 2012.
» Lahaina Noon ("overhead sun") returns to the Hawaiian Islands in July. In the tropics, the sun passes overhead twice during the year. On these two days, at local noon, the sun will be exactly overhead, and an upright object such as a flagpole will have no shadow. This phenomenon occurs only in the tropics. Since all of the main Hawaiian Islands are in the tropics, all of the main islands have two overhead sun days, one in May and one in July.
The "overhead sun" date for July varies depending on how far north or south you are. Here are the July Lahaina Noon days and times: Lihue, July 11, 12:42 p.m.; Kaneohe, July 15, 12:37 p.m.; Honolulu, July 16, 12:37 p.m.; Kaunakakai, July 16, 12:34 p.m.; Lanai City, July 18, 12:34 p.m.; Lahaina, July 18, 12:33 p.m.; Kahului, July 18, 12:32 p.m.; Hana, July 18, 12:30 p.m.; Hilo, July 24, 12:26 p.m.; Kailua-Kona, July 24, 12:30 p.m.; South Point, July 28, 12:28 p.m.
Pluto encounter
When the New Horizons robot spacecraft flies past Pluto on July 14, it will be the first mission from Earth to encounter that distant dwarf planet. Since New Horizons was launched in early 2006, a lot has changed in terms of our understanding of Pluto. As the mission sailed through space, astronomers discovered two more Plutonian moons; shortly after New Horizons’ launch, Pluto’s status changed from planet to dwarf planet.
As a tie-in to the event, Bishop Museum is presenting a new program, "Pluto: Exploring New Horizons," at 2:30 p.m. daily in July except Tuesdays, when we are closed. The program lasts 35 minutes and is included in museum admission.
