21 July 2015

Southern Summer Skies

Facing South in the Summer
Facing south in the summer reveals a rich region of the night sky featuring the heart of the Milky Way and several excellent zodiac constellations. If you have a clear horizon to the south, the constellation Scorpius dominates the space with a long curving shape that winds around the horizon back to the tip of the tail of the scorpion, a feature called the Cat's Eyes, Shaula and Lesath.

For the next few months, Saturn is lurking next to the head of the scorpion, adding a bright highlight to the pattern. Scorpius and neighboring Sagittarius (to the east) are found directly in the center of the galaxy so there are numerous deep space objects to be found in the vicinity, making it one of the best places to enjoy with binoculars. You can move from spot to spot and never run out of interesting objects to see. This week the gibbous Moon drifts through that region of the sky so the darkness will be somewhat spoiled, but I find it good to get to know constellations when there is moonlight as well as when you have complete darkness. With moonlight you can learn the basic outline of the constellation, and without moonlight the deeper objects will emerge and reveal themselves to the careful viewer.

Image courtesy Sky & Telescope. 

13 July 2015

Pluto and New Horizons

As an amateur astronomer, Pluto is a tantalizing target to find, but one that is quite out of reach for all except the most committed amateur astronomers with the best possible equipment. And even if you locate it in a telescope it will be an extremely faint pinprick of light. So it has never entered my interest until this week. Instead of viewing it from a distance, humanity has finally launched a probe to fly by the planet (ok, dwarf planet) and offer up a close-up during its close passage.

Almost 10 years after launching, New Horizons arrives at Pluto this week. The initial pictures are promising, and I am confident we will be overwhelmed with new data and new discoveries in the days ahead, and in the weeks and months that follow as the vast collection of sensor data is gradually transmitted back to Earth. I loved every major interplanetary mission growing up, watching Pioneer and Voyager vastly expand our knowledge of the Solar System. New Horizons will provide the icing on the interplanetary cake; with our first ever close up of a dwarf planet and a peek into the Kuiper Belt.

Stay tuned to NASA for a busy week of discovery: https://www.nasa.gov/mission_pages/newhorizons/main/index.html 

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.

31 May 2015

Jupiter and Venus Closing In

Jupiter and Venus
The two brightest objects in the night sky (after the Moon) are closing in for a very close encounter in June. Each evening you can watch the gradual change as Jupiter descends in the west toward Venus. As both planets are on the same line of travel across the sky (the Ecliptic), they pass near each other typically once per year. This is going to happen in 2015 in late June. For now, check out the daily movement in the west after sunset. I'll write more about the close encounter in the month of June.

Image courtesy Sky & Telescope.

18 May 2015

Get Involved: Star Parties and Astronomy Lectures

Each month, the public is welcome to join regional events affiliated with the San Francisco Amateur Astronomers (SFAA). The club supports local 'star parties' and hosts lectures of deep scientific interest. These events are free and open to the public.

SFAA Lectures: Each month, the SFAA club meeting includes a lecture by a prominent astronomer or astrophysicist on a topic of general interest. Topics have included exo-planet research, dark matter, space telescopes, stellar research, and more. Check the SFAA website and join the club on the third Tuesday of each month at the Presidio of San Francisco.

Lectures and Star Parties on Mt. Tam: Each month (May-Oct) the SFAA joins with the Friends of Mt. Tam and the California State Park System for an evening of astronomy talks and star gazing on the west peak of Mt. Tamalpais in Marin County. The evenings are a wonderful, family-friendly experience that feature star gazing with extraordinary telescopes brought up to the mountain by members of the SFAA for public viewing. The conditions on Mt. Tam are quite dark and feature great views of deep space objects, planets, and other objects in the night sky.

City Star Parties: Each month the SFAA hosts star parties in San Francisco at one of three locations; Lands End, the Exploratorium, and the Presidio. These star parties are focused on astronomy learning and viewing of brighter objects such as the Moon and planets. The schedule is on the SFAA website.

Hope to see you at an upcoming event.

29 April 2015

The Springtime Constellation Bootes and M3

Bootes, Arcturus and M3
Spring marks the arrival of the constellation Bootes and the brilliant orange giant star Arcturus. Looking east shortly after sunset, Arcturus is immediately visible as the brightest celestial object in that part of the sky, and Bootes is easy to spot alongside the star and bordering the Big Dipper.

Bootes is an ancient constellation named for a herdsman, and it's his twin brother that drives the plough in the Big Dipper (as the constellation is referred to as a plough in some cultures). Bootes himself is marked by the familiar pattern to the right, sometimes called an ice-cream-cone-shape or a kite with Arcturus at the tip of the tail of the kite.

One of the features of Bootes is that it is a quick guide to one of the most impressive globular clusters visible from the Northern Hemisphere, M3. This cluster is in the halo of the Milky Way galaxy and like its famous neighbor M13 (the Great Globular Cluster), is a densely packed region with half a million stars, 34,000 light years above the disk of the Milky Way. In binoculars or a telescope it is a marvelous sight and one that is a worthwhile endeavor to seek on a dark night.

Astro Bob has an excellent article on Bootes so enjoy his view for another perspective.

Image courtesy Astro Bob.