29 June 2015

The Great Conjunction

The Great Conjunction
When the two brightest celestial objects in the night sky (excepting the Moon) pass next to each other, this is a grand event on an astronomical scale. Jupiter and Venus are doing just that, passing less than a Moon's diameter from each other in a great conjunction, peaking on Tuesday June 30th. A casual spectator should have no trouble seeing the pair, particularly after the glare of sunset subsides (around 9:00 pm or later on the west coast of the USA).

Enjoy this rare and beautiful pairing, made more special by the fact that it's the Queen of Love and the King of the Solar System in close proximity. Who knows what might come of that!

Image courtesy of Sky & Telescope.

27 June 2015

Three Summer Stars in the Milky Way

The arrival of the warm and long days of summer also marks the return of the Summer Triangle and three of the brightest stars in the night sky, Deneb, Altair and Vega. I wax poetically about these sparkling gems when I give a star talk during warm summer nights, with each of the three stars bringing us a unique perspective. All three are in or near the band of the Milky Way, so a close up look at these through binoculars reveals the depths of our home galaxy. This week the Astronomy Picture of the Day (APOD) featured detailed descriptions of these stars and an excellent photograph shown here. Their article says it best.

Three Stars of the Summer Triangle
From APOD: "Rising at the start of a northern summer's night, these three bright stars form the familiar asterism known as the Summer Triangle. Altair, Deneb, and Vega are the alpha stars of their respective constellations, Aquila, Cygnus, and Lyra, nestled near the Milky Way. Close in apparent brightness the three do look similar in these telescopic portraits, but all have their own stellar stories. Their similar appearance hides the fact that the Summer Triangle stars actually span a large range in intrinsic luminosity and distance. A main sequence dwarf star, Altair is some 10 times brighter than the Sun and 17 light-years away, while Vega, also a hydrogen-fusing dwarf, is around 30 times brighter than the Sun and lies 25 light-years away. Supergiant Deneb, at about 54,000 times the solar luminosity, lies some 1,400 light-years distant. Of course, with a whitish blue hue, the stars of the Summer Triangle are all hotter than the Sun."

It's easy to spot the majestic asterism of the Summer Triangle rising out of the east after the late sunsets of June. Take a few minutes to appreciate the three stars that make up this distinctive pattern in the night sky.

Image and text courtesy of NASA and Rogelio Bernal Andreo.

18 June 2015

Approaching a Conjunction

Evening Trio
Each day the planets Venus and Jupiter are drawing closer together in the evening sky, as Jupiter gradually sinks into the western twilight and Venus holds course. The two will have a close encounter (conjunction) on June 30th, but already the two are a striking pair in the evening sky, made more interesting by the waxing crescent Moon this weekend. Look for the trio just after sunset (around 8:45 pm in San Francisco) and watch them become more and more brilliant as the sunset sky turns to dusk and eventually to darkness.

Image courtesy of Sky & Telescope.