Summer is coming, contrary to what you may have heard on a certain popular television show. The days are longer and the nights are milder. In most of the country, parka weather at night gives way to sweater weather or even short sleeves.
And those late summer evenings — along with cool, predawn summer mornings — are an invitation to visit the night sky. While it can be filled with surprises, the night sky is also home to regular, predictable astronomical events. To sky observers these events become like old friends, to be greeted anew each time they come around.
NASA provides a handy website that will generate a customized calendar of sky events, for the month or a whole year, with times adjusted to your time zone. Sky & Telescope and Sea and Sky also provide annotated night sky calendars for 2019, with helpful thumbnail descriptions of notable night sky events.
This summer kicks off with the most spectacular of all sky show events, a total solar eclipse — but alas, not for most of us. The total eclipse on July 2 will be visible only from Chile and Argentina and the southern Pacific Ocean, though much of South America will see a partial eclipse of the sun.
Saturn at Opposition (July 9)
On this night Saturn is lined up exactly on the opposite side of the sky from the sun (thus the name Opposition). It rises in the east at just about sunset and sets around dawn. And as Sea and Sky points out, this is also the point when Saturn is closest to Earth and at its brightest in our night sky.
While Opposition marks the moment of closest approach, Saturn will be particularly bright in the sky for weeks. A medium-sized telescope is needed to see the rings of Saturn, but you might glimpse its large moon Titan with a good pair of binoculars.
Delta Aquarids Meteor Shower (July 28)
Of all astronomical events, meteor showers are the closest to home: We spot meteors as they burn up in Earth’s upper atmosphere less than 100 miles above the ground. At the same time, the Delta Aquarid meteor shower is made up of visitors from the outer solar system, specks of dust and gravel associated with comets Marsden and Kracht. (The meteors are unrelated to the star Delta Aquarii.)
The meteor shower takes place each year when Earth’s orbit intersects the orbit of the comets. The shower is spread over several nights, but peaks on the night of the 28th (actually after midnight, on the early morning of the 29th). Best seen in dark skies; expect to see about 20 meteor flashes an hour.
Mercury at Elongation (August 9)
Mercury is the closest planet to the sun, which means that, as seen from Earth, it never strays very far from the sun in the sky, and is only visible during dawn or dusk. For this reason it is the most elusive of the bright planets, and even people familiar with the night sky may never have seen it.
Elongation marks the point in Mercury’s orbit when it appears farthest from the sun in the sky, making it easiest to see. Look for it low in the eastern sky just before dawn on the early morning of the 9th. Mercury moves a lot from night to night, but you might also be able to catch a glimpse of it a couple of mornings just before or after Elongation.
Perseids Meteor Shower (August 12)
Unlike the fairly subtle Delta Aquarids, the Perseids are among the most dramatic meteor showers. They can be seen over a week or so, peaking on the night of the 12th. As Sea and Sky notes, the Perseid shower can produce about 60 meteors an hour — an average of one every minute or so — and is also known for bright meteors. A nearly full moon will tend to drown out the fainter meteors, but the bright ones should still put on a good show.
Neptune at Opposition (September 9)
On this night it is Neptune, the outermost major planet, that is just on the opposite side of the sky from the sun. But this is one sky show that you probably won’t actually see, because Neptune is not visible to the naked eye.
It can be spotted with good binoculars — but you need to know exactly where to look. And because even most telescopes only show Neptune as a bluish speck of light, you need to know the stars around it in order to recognize it as a wandering interloper. Consider this an advanced sky observer’s project!
And as you follow the calendar of astronomical events, don’t forget the summer night sky show that happens on every clear night. In rural areas with dark skies, look toward the south to see the brightest part of the Milky Way — marking the center of our galaxy — spread across the southern constellations Sagittarius and Scorpius. If you haven’t met our galaxy yet, let this be the summer that you make its acquaintance.