While we lose the Southern Cross from the Hawaiian Islands by the time July starts, the month does provide a last chance to catch the brilliant stars Alpha and Beta Centauri, the best summertime stars we see in Hawaii and which are not visible from most of the United States.

Along similar lines, the overhead sun returns in Hawaii in July, a phenomenon unique to the tropics and which never occurs in the other 49 states.

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; the sun is never overhead in any other part of the planet. Since Hawaii is the only tropical state, it’s also the only state that experiences the overhead sun.

Throughout the main islands, the first overhead sun of the year occurs in May and the second in July. The date varies depending on how far north you are from the equator. Thus, for Lihue on Kauai, the July overhead sun occurs July 12. Farther south, on Hawaii island, the overhead sun occurs nearly two weeks later, on July 24, in both Hilo and Kailua-Kona.

Here in the islands a term we often use for zenith noon is “Lahaina Noon.” This is a modern term, selected by Bishop Museum in a 1990 contest held to select a name for the phenomenon. The term “La haina” means “cruel sun” in Hawaiian.

Here are July overhead sun dates for several locations: Lihue, July 12, 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, 12:27 p.m.; Kailua-Kona, July 24, 12:30 p.m.; South Point, July 27, 12:28 p.m.

Dueling giants

Since many of the great sights for the month are seen on our July 2017 sky map, I’ll use that map as our point of reference. As with all of our monthly star maps, the July map is good for 10 p.m. early in the month, 9 p.m. in the middle of the month and 8 p.m. at the end of the month.

At map time, look for the bright white dot of Jupiter about one-third of the way up in the western sky. Jupiter is the brightest dot in evening sky; it shines much brighter than any star, so it pops out easily. The bluish-white star Spica, about 10 degrees (the width of your palm at arm’s length) to the left of Jupiter, shines brightly, but Jupiter still outshines it by 20 times.

In early July, Jupiter will set in the west at 12:30 a.m.; by the end of the month, by 10:45 p.m. On Saturday, look for the just-past-first-quarter moon making a triangle with Jupiter and Spica.

If you return to our star map, Saturn is about halfway up in the southeast at map time. Saturn has a distinctive yellow-white color. While it’s nowhere near as bright as Jupiter, Saturn does shine nicely. This makes Saturn about 2.5 times brighter than the star Antares in the constellation of Scorpius the Scorpion, the first-magnitude star to the right of Saturn.

In early July, Saturn will be due south at 11:30 p.m. and will set in the west at 4:45 a.m., just as the first light of dawn starts to break. By the end of the month, Saturn is due south at 9:20 p.m. and sets by 2:30 a.m.

Saturn’s rings are perhaps the most beautiful telescope sight of all. The rings should be even more striking than usual this season. The rings are tilted 27 degrees to our line of sight this summer, the best “tilt” since 2003; this means that the rings are exceptionally well-angled for good telescope viewing.

Constellations

In addition to featuring good views of Jupiter and Saturn, the July star map shows you how to find many well-known constellations as well as the Southern Pointers — stars you can’t see from most of the rest of the U.S. While the Southern Cross has left our sky, as it does every July, the Southern Pointers (Alpha and Beta Centauri) can still be seen on the map, low in the south. The brighter of the two, Alpha Centauri, is the third-brightest star of all, and the brightest star you can see in the July evening sky. Beta Centauri is the 11th-brightest star.

The constellation of the Scorpion, or Maui’s Fishhook, is due south on our map. It is one of the most striking shapes in the sky; its brightest star, Antares, has a distinct orange tint to it. To the left of Scorpius is Sagittarius the Archer, aka “the Teapot.”

Our map shows the star Arcturus high in the western sky. The star is known as Hokule‘a in Hawaiian, “the star of gladness.” You can also see the Big Dipper in the north, its cup pointing to the North Star and its handle pointing to Arcturus.

The summer triangle is rising in the northeast by map time; the triangle is made of the bright stars Vega, Altair and Deneb, pulled from three separate constellations to make a big triangle in the sky.

Other July sky events

Venus lights up the hours before dawn throughout July. Venus rises in the east right around 3 a.m. and is about a third of the way up in the east at daybreak. Venus shines many times brighter than even Jupiter. Venus will remain in this role as a predawn beacon all the way till the end of October.

The elusive planet Mercury is visible for all of July, though it clings to the western horizon at dusk. In early July, the planet is a mere four degrees (the width of two fingers at arm’s length) above the western horizon at about 7:50 p.m., when it gets dark enough to see it by 8:10 p.m. From midmonth to the end, the planet is nearly 10 degrees above the western horizon when it gets dark around 7:50 p.m., giving you almost an hour to find it before Mercury sets at 8:40 p.m.

While not one of the more striking showers, the Southern Delta Aquariid meteor shower in late July does occur this year during a time when the moon is out of the way, which will improve the viewing odds.

The peak time: the early hours of the morning on July 30, from 12:01 a.m. to dawn on that day, though all mornings from July 27 through Aug. 1 should show increased meteor activity. Search the eastern and southern skies for streams of light; under ideal sky conditions, viewers can see up to 25 meteors an hour.

Mike Shanahan is Bishop Museum’s director of visitor experience and planetarium. Reach him at mikes@bishopmuseum.org.