Last month, we called attention to a celestial assembly involving the moon, two shiny stars and two shiny planets adorning our western evening sky.
Now, one other, similar gathering will happen this week; an array that may change night to nighttime as we transition from the spring into the summer season with the summer solstice on June 21. Here’s a take a look at the how the celebs of Gemini will shine with the moon, Mars and Venus as summer begins.
Related: The brightest planets in June’s night sky (guide)
Monday, June 19: Twin Gemini stars Castor and Pollux
The week’s skywatching feast begins Monday evening on June 19, the “Juneteenth” holiday in the USA. Starting at 45 to 60 minutes after sundown, look low to the west-northwest horizon. There, one can find a slender sliver of a crescent moon, lower than two days after recent phase. And directly above it it’s best to give you the chance to make out two stars, Pollux and Castor, marking the heads of the Twin Brothers, Gemini. There appears to be some evidence that after they were first chosen to represent the Twins, they really gave the impression to be twin stars of equal brightness.
If true, either Pollux has grown brighter or Castor had faded within the night sky, for there’s a noticeable difference between them now. Pollux now appears a bit of over twice as shiny as Castor and can also be certainly one of the 57 standard navigational stars. But Castor is the true “star” of Gemini. Even though it appears as a single star with the unaided eye, it is definitely a system of six stars. In a telescope we see two, Castor A and B. Moreover, each A and B are themselves doubles, though much too near be separated optically (called spectroscopic doubles). Finally, well off to the south of the primary pair is Castor C, a pair of dim red stars.
Tuesday, June 20: Crescent moon near Venus
Tuesday evening, June 20: A rather wider crescent moon can have shifted away to the upper left of the Twin stars and can be situated roughly a dozen degrees to the lower right of the dazzler of the evening sky, the planet Venus. Your clenched fist held at arm’s length measures roughly 10 degrees, so on tonight, the moon and Venus can be separated by just a bit of over one fist’s width within the sky.
Venus, in fact, continues to simply outshine all the things within the evening sky, save for the moon itself. It currently shines at magnitude -4.6. In comparison with Pollux and Castor, Venus outshines these luminaries by an element of 100.
Read more: The Native American night sky: 7 starry sights to see
Wednesday, June 21: Summer solstice and moon
Wednesday, June 21: That is the summer solstice and the primary official day of summer for the Northern Hemisphere and on this evening the convocation of moon, stars and planets can be at its most pleasing to the attention. About an hour before the sun sets, face due west and look about halfway up within the sky to search out the crescent moon.
Now, if you have got binoculars, train them on the moon and look to the left and barely below the crescent and you should not have any problem in picking out Venus, appearing as a shiny speck of white light against the blue of the daytime sky. And once you have positioned it with binoculars, attempt to see when you can find it with just your eyes alone. If you have got good vision and your sky is transparent and never too hazy, it’s best to have little trouble seeing Venus through the daylight.
In fact, once the sun has set and the sky darkens, each the moon and planet will command everyone’s attention to the western sky for nearly three hours after sunset.
But Venus just isn’t the one planet that’s visible on tonight.
About 4 degrees to its upper left, appearing to shine somewhat feebly, can be Mars. You’ll likely need binoculars to see it in any respect in the brilliant twilight even after Venus becomes obvious. At magnitude +1.7, Mars now only ranks as a second-magnitude object and shines greater than six magnitudes fainter or about 331 times dimmer than Venus! One reason is that Mars is barely about half the scale of Venus and is currently 200 million miles (322 million km) from Earth in comparison with just 53 million miles (85 million km) for Venus.
And situated a few dozen degrees to the upper left of Mars, is yet one more shiny twinkler: the bluish 1st-magnitude star Regulus, brightest star of Leo the Lion. Regulus was noteworthy to ancient skywatchers because it was certainly one of the 4 “royal” stars which were supposed way back to rule over the 4 quarters of the heavens.
Thursday, June 22: The moon joins Mars and Regulus
The moon, now a fat crescent nearly five days past recent phase, will form a somewhat wide isosceles triangle with the star Regulus and Mars.
The moon will mark the vertex angle with the “legs,” measuring roughly 6 degrees, formed by the Regulus/moon and Mars/moon sides of the triangle, and Regulus and Mars separated by roughly 10 degrees marks the bottom of the triangle.
Not an “official” meeting
It might also appear that Venus is racing rapidly eastward each night and ultimately will reach the slower moving Mars. That scenario, nonetheless, won’t come to pass.
Venus already arrived at its biggest angular distance east of the sun on June 4, so from our viewing perspective it’s now swinging around in its orbit and is heading back within the direction of the sun. Although seemingly chasing Mars down within the evening sky, the 2 won’t ever get together.
The truth is, from June 19 through July 10, Mars undergoes a “quasi-conjunction” with Venus because the more good world draws close but never quite catches up. A quasi-conjunction is defined as two planets approaching to inside 5 degrees of one another — half the width of your clenched fist held at arm’s length — without an actual conjunction in right ascension. They’ll appear closest together on July 1, after they can be separated by just 3.57 degrees.