Sky watching is very good in the islands this June. There is a trio of bright planets in the evening sky through the month, including Mars, which remains unusually bright through the month. Jupiter and Saturn are clearly visible from the mid-evening sky as well. We have lost all of the winter constellations such as Orion and Taurus, but the classic starry patterns of summer, from Scorpius the Summer Triangle, are now on parade.
Planets in June
Mars, Saturn and Antares: the triangle continues
Throughout June 2016, look for the very distinctive triangle formed by Mars, Saturn and Antares, the brightest star in the Scorpion. While Mars’s brightness peaked in late May at a whopping minus 2.08 magnitude, it remains brilliant, and is by far the brightest member of the triangle. Orange-white Mars shines at minus 2 magnitude in early June and at minus 1.4 at the end of the month, still about as bright as the brightest star.
The other two dots in the triangle are the planet Saturn, the second brightest dot at 0 magnitude, shining with its distinctive yellow-white color; and the star Antares, the least brilliant of the three dots at 1.03 magnitude, showing an orange glow that’s similar to much-brighter Mars. (Antares’ name means ‘the rival of Mars,’ due to the similarity in color.)
Throughout the month the three dots make a long, narrow triangle; check out our June star map for their basic configuration. At the star of June, look for the trio rising in the southeast at dusk, with blazing Mars on top; Antares will be 12 degrees (a little more than the width of a fist) below Mars, and Saturn will about three fingers to the left of Antares. By midnight in early June the triangle will be halfway between the southern horizon and the top of the sky; by this time of night, the triangle will be on its side with Mars leading the way. By 4:30 a.m.in early June the triangle plunges for the horizon in the west, Mars now the lowest dot and Saturn and Antares above.
Since stars and planets generally rise (and set) about 30 minutes earlier each week, things will look different at the end of June. By then, the triangle of Mars, Saturn and Antares will be high in the south as it gets dark at 8 p.m., with still-blazing Mars leading the way; the red planet remains the point of a narrow triangle, with dimmer Saturn and Antares each about the width of two palms to the left of Mars. The triangle hits the western horizon in the early hours of the morning in late June, with Mars plunging below the horizon at 2:30 a.m. and then Saturn and Antares taking the plunge around an hour later.
Look for the waxing gibbous moon (that is, a moon that is between first quarter phase and full phase) visiting the triangle on the nights of June 16 – 18.
On June 3, Saturn is in opposition. When an outer planet like Saturn is in opposition, this means there is a straight line between sun, earth and the planet. The ringed planet will rise at sunset, be overhead all night, set at dawn, and shines at its brightest, at exactly 0 magnitude.
For May and June 2016, we have the rare sight of Jupiter being rivaled in brightness by Mars (normally there is no contest here, Mars being usually much the fainter of the two dots). At the start of June, look for Jupiter high in the southwest at dusk (2/3 of the way between the horizon and the zenith), shining at minus 2.04; after you locate it in the west, compare its brightness to Mars, rising in the east. While white Jupiter is just a little brighter than minus 2.0 Mars, the distinctive orangey color of Mars stands out so much that the two planets look almost identical in brightness.
Jupiter sets in the west at 1 a.m. in early June. By month’s end, Jupiter is only about halfway up in the west at dusk, and sets around 11 p.m.
From June 1 through about June 15, Mercury rises in the east just after 4:30 a.m. and is about ten degrees above the east horizon at daybreak. By the 15th it shines at minus 0.2 magnitude. For the week after that, till about the 22nd, Mercury comes up in the east around 5 a.m. and is visible for only about 20 minutes before being washed out by the day.
Venus is the only naked-eye planet we have no chance of seeing in June 2016; it passes behind the sun and we won’t see it again till July.
Other sky events in June
Summer begins on June 20 at 12:35 a.m. Hawai‘i Standard Time (22:35 on June 20 Universal Time). This is the longest day for the northern hemisphere and the shortest for the southern hemisphere. On this day in Honolulu we have over thirteen hours of daylight and just under eleven hours of night.
Many visitors who come to our islands from temperate zones are surprised by the fact that our longest day on June 21 is only a little over 13 hours; in Seattle on the same day, for example, there is about 15.5 hours of day and only 8.5 hours of night. The seasons are caused by the tilt of the earth, and in June and July, the northern hemisphere is tilted in towards the sun. However, the closer you are to the equator, the less that tilt matters. In fact, day and night are equal all year round on the equator; and in the Hawaiian Islands, just 1500 miles north of the equator, we only have a two hour difference between the longest day in late June and the shortest day in late December.
In the islands, June is always the last time to find the Southern Cross, or Crux. After June, Crux vanishes into the sun, reappearing in the predawn sky in December.
At dusk in early June (8 p.m.), look due south; the cross will be exactly south. When the Cross is due south, it is at its highest point, even though still quite low from O‘ahu. By dusk, the stars Alpha and Beta Centauri have also risen, and appear to the left of Crux. Find these two first; they are brighter than the stars in Crux and will pop out sooner. Once you’ve found these two brilliant stars, go right, and these two stars will point you to Gacrux, the top star in the Cross. By 10 p.m., the time the star map is good for in early June, Crux is still visible in the southwest but is heading for the horizon; the star map gives a good idea of what Crux and Alpha and Beta Centauri look like, which will help if you try to cross-hunt earlier in the evening.
If you go Crux-hunting in the latter half of June, use our June star map to locate the cross, low in the southwest. The map is good for 9 p.m. in mid-June and right at 8 p.m., dusk, in late June. Make sure you have a flat southwest horizon, such as you get by looking over the ocean. As the Cross approaches the southwest horizon, it becomes even more important to use Alpha and Beta Centauri, the two ‘southern pointer’ stars, to find your way to the cross. They are due south on the map.
June star map
Like all of our monthly maps, this one is good for 10 p.m. on the first day of the month, 9 p.m. for the middle of the month, and for 8 p.m. at the end.
One key constellation that’s missing is Orion. Orion vanishes into the sun every year in late May, and does not return to the predawn sky till late July.
The Big Dipper is high overhead in June; at our lower latitude we do lose the Dipper in the fall evening sky, but spring and summer are good times to catch this famous gathering of stars, called Nā Hiku in Hawaiian (“the Seven”). In the south we now have a good view of Scorpius (“Maui’s Fishhook” in the Hawaiian Islands), whose brightest star Antares forms a triangle with Mars and Saturn this summer.
The summer triangle – three stars pulled from three different constellations – is rising in the east, with the brightest of the three, Vega, leading the way. (This is a regular starry pattern that returns every summer, and is different of course from the special June 2016 triangle of Mars, Saturn and Antares mentioned above.)
Moon Phases (Hawaiian Time Zone):
New: June 4
First Quarter: June 11
Full: June 20
Third Quarter: June 27