The night sky regularly offers skywatchers once-in-a-lifetime experiences, this June’s
rare alignment of all the planets in the solar system serving as a perfect example.
Two predawn dates are particularly noteworthy, June 4 and the 24th.
For months now, the planets have been readily accessible and enthralling, wandering in
and out of conjunctions and forming stunning geometric patterns. By the morning of the 4th, all the planets in the solar system, both visible and telescope-dependent, will line up in an ascending straight line spanning 91 degrees from Mercury to Saturn.
The downside, on this morning at least, is that Mercury breaks the horizon by 5 am,
deep in the glare of the 5:33 am sunrise. Additionally, it gains only 6½ degrees before sunrise and will be difficult, though not impossible, to observe. Situate yourself on an unobstructed throw of land facing due east with a pair of binoculars, avoiding of course – at all cost – looking at the sun even fleetingly.
What’s compelling about the morning of June 4 is that the planets haven’t been in this
particular arrangement for nearly 100 years. What’s more, the naked eye planets are visible in the order of their orbits’ distances from the sun. Saturn, high in the southern sky between constellations Aquarius and Capricornus, is followed by Jupiter 39 degrees to its west. Mars is next in line at 4 degrees from Jupiter, and another 30 degrees to the west you’ll find this year’s pre-dawn staple, Venus. Mercury brings up the rear, 18 degrees to its left.
The next time this line-up appears exactly like this will be 2041, well within the lifespan
of many skywatchers alive today. Still, considering the direction that the course of human events seems to be heading, it’s perhaps best to hedge and take the time admire this rarity while you can.
Think of the skywatching in the morning of the 4th as a dry run for the June 24 spectacle.
Although not as a rare bird, this planetary apparition is much better. Mercury rises before 4:30 am, doubles its altitude and glows four times brighter at magnitude ˗0.2. The waning crescent moon, gloriously splashed with earthshine, sits between the messenger god and the brilliant goddess of love, representing the Earth.
It’s not just the naked eye planets that deserve all the attention. Skywatchers with
telescopes should easily find Neptune between but closer to Jupiter than Saturn. Uranus is below and to the northeast of the crescent moon. Note that these two ice giants are not in the aforementioned order since they are both beyond Saturn’s orbit.
Perhaps it is a good thing that Pluto has been relegated to minor planet status because it’s far to the south on the 24th, out of alignment and would spoil the whole effect.
The month ends with one more conjunction. Size 3.89 Venus will be 2½ degrees
from a beautiful crescent moon, the closest of their pairings for the year. Watch an even slimmer crescent moon sitting 3½ degrees from Mercury on June 27
The summer solstice is at 3:14 am June 21, the moment when the sun is farthest north in the celestial sphere. The first day of summer is the longest of the year at 15 hours, 1 minute and 1 second in length. The earliest sunrises are at 5:31 am June 10-18, and the latest sunsets are at 8:34 pm June 25-29.
The full moon is at 5:51 am June 14 and is called the Full Strawberry Moon.