GAAC Program note for June 12 2015

Save the date! Friday June 12 @8:00 is our annual Welcome to Amateur Astronomy Night.

We'll have telescopes of every size and description set up inside the LCC for you to inspect and ask their owners about.  What are the benefits of that particular scope? What can you see? How much did it cost? Get lots of answers while munching a brownie. And that's not all:

You'll enjoy six quick, colorful ten-minute presentations on different Astronomy topics, featuring GAAC faves Mario Motta, Glenn Chaple, Elaine Kolaczkowski, Jim Koerth, Alan Winter, and John Hobbs.

Our program:

  • What you need to know to get started in astronomy
  • How to buy your first scope, and what you need to do before you buy
  • The upcoming 2017 solar eclipse, how and where to view it
  • All the best astronomy gadgets, from the gadget meister
  • The how's and why's of binocular astronomy -- seeing more with less
  • How to do astrophotography without a telescope (with examples!)

Of course we'll have the usual goodies and wonderful conversation you've come to enjoy from GAAC.

Don't miss this annual overview of everything you need to know to begin exploring the cosmos in the company of very nice people.

Sky Object of the Month – June 2015

Messier 3 (NGC 5272) – Globular Cluster in Canes Venatici
by Glenn Chaple

As May gives way to June, backyard astronomers begin to anticipate the arrival of summer’s globular clusters, and with good reason. The globular-laden constellations Ophiuchus, Scorpius, and Sagittarius are beginning to show up in the early evening sky. We needn’t wait for this globular onslaught. Already well-placed for after-sunset viewing is Messier 13 in Hercules - grandest of all the northern sky globulars. Also available is Messier 3 in Canes Venatici. Compared to M13, it’s slightly fainter (magnitude 6.2 to M13’s 5.8) and smaller (18 arcminutes to 20 arcminutes). Looks can be deceiving, as M3 is about half again as distant as M13 (33,000 LY to 26,000 LY) and is intrinsically the larger of the two.

M13 is my globular cluster of choice at public star parties. Conveniently placed between zeta (ζ) Herculis and eta (η) Herculis in the “Keystone” of Hercules, it’s quick and easy to locate – something I consider when a line of people is waiting by my telescope.

When time constraints aren’t an issue, I like to place M3 on the observing menu. It isn’t really all that hard to find, being bright enough to be easily spotted in binoculars and finderscopes (it’s even been seen without optical aid by keen-eyed observers in dark-sky locations). To capture M3, point your telescope midway between alpha (α) Canum Venaticorum (Cor Caroli) and alpha (α) Bootis (Arcturus), but slightly closer to the latter (refer to the accompanying finder chart). A low-power sweep should pick up a roundish smudge of light. Switch to higher magnitudes, and you’re in business!

While most globular clusters require apertures of 6 inches and above to resolve their individual stars, M3 can be partially resolved in small-aperture scopes. The accompanying sketch shows its appearance as seen through a 4.5-inch reflector. Visible is the core and a smattering of stars near its outer edge. Large telescopes bring the outermost reaches of M3 into view – a spectacular sight, as an image taken by Amateur Telescope Makers of Boston President Neil Fleming shows. Rotate the Fleming photo about 30 degrees clockwise, and scale and orientation of both fields will be identical.

Think of this as you gaze at M3. You’re looking at a half million stars packed into a sphere just 190 light years across!

 

 

 


NASA Space Place Column, April 2015

Is the Most Massive Star Still Alive?

By Ethan Siegel

The brilliant specks of light twinkling in the night sky, with more and more visible under darker skies and with larger telescope apertures, each have their own story to tell. In general, a star's color correlates very well with its mass and its total lifetime, with the bluest stars representing the hottest, most massive and shortest-lived stars in the universe. Even though they contain the most fuel overall, their cores achieve incredibly high temperatures, meaning they burn through their fuel the fastest, in only a few million years instead of roughly ten billion like our sun.

Because of this, it's only the youngest of all star clusters that contain the hottest, bluest stars, and so if we want to find the most massive stars in the universe, we have to look to the largest regions of space that are actively forming them right now. In our local group of galaxies, that region doesn't belong to the giants, the Milky Way or Andromeda, but to the Large Magellanic Cloud (LMC), a small, satellite galaxy (and fourth-largest in the local group) located 170,000 light years distant.

Despite containing only one percent of the mass of our galaxy, the LMC contains the Tarantula Nebula (30 Doradus), a star-forming nebula approximately 1,000 light years in size, or roughly seven percent of the galaxy itself. You'll have to be south of the Tropic of Cancer to observe it, but if you can locate it, its center contains the super star cluster NGC 2070, holding more than 500,000 unique stars, including many hundreds of spectacular, bright blue ones. With a maximum age of two million years, the stars in this cluster are some of the youngest and most massive ever found.

At the center of NGC 2070 is a very compact concentration of stars known as R136, which is responsible for most of the light illuminating the entire Tarantula Nebula. Consisting of no less than 72 O-class and Wolf-Rayet stars within just 20 arc seconds of one another, the most massive is R136a1, with 260 times the sun's mass and a luminosity that outshines us by a factor of seven million. Since the light has to travel 170,000 light years to reach us, it's quite possible that this star has already died in a spectacular supernova, and might not even exist any longer! The next time you get a good glimpse of the southern skies, look for the most massive star in the universe, and ponder that it might not even still be alive.


Images credit: ESO/IDA/Danish 1.5 m/R. Gendler, C. C. Thöne, C. Féron, and J.-E. Ovaldsen (L), of the giant star-forming Tarantula Nebula in the Large Magellanic Cloud; NASA, ESA, and E. Sabbi (ESA/STScI), with acknowledgment to R. O'Connell (University of Virginia) and the Wide Field Camera 3 Science Oversight Committee (R), of the central merging star cluster NGC 2070, containing the enormous R136a1 at the center.

NASA Space Place Column, March 2015

The Cold Never Bothered Me Anyway

By Ethan Siegel

For those of us in the northern hemisphere, winter brings long, cold nights, which are often excellent for sky watchers (so long as there's a way to keep warm!) But there's often an added bonus that comes along when conditions are just right: the polar lights, or the Aurora Borealis around the North Pole. Here on our world, a brilliant green light often appears for observers at high northern latitudes, with occasional, dimmer reds and even blues lighting up a clear night.

We had always assumed that there was some connection between particles emitted from the Sun and the aurorae, as particularly intense displays were observed around three days after a solar storm occurred in the direction of Earth. Presumably, particles originating from the Sun—ionized electrons and atomic nuclei like protons and alpha particles—make up the vast majority of the solar wind and get funneled by the Earth's magnetic field into a circle around its magnetic poles. They're energetic enough to knock electrons off atoms and molecules at various layers in the upper atmosphere—particles like molecular nitrogen, oxygen and atomic hydrogen. And when the electrons fall back either onto the atoms or to lower energy levels, they emit light of varying but particular wavelengths—oxygen producing the most common green signature, with less common states of oxygen and hydrogen producing red and the occasional blue from nitrogen.

But it wasn't until the 2000s that this picture was directly confirmed! NASA's Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) satellite (which ceased operations in December 2005) was able to find out how the magnetosphere responded to solar wind changes, how the plasmas were energized, transported and (in some cases) lost, and many more properties of our magnetosphere. Planets without significant magnetic fields such as Venus and Mars have much smaller, weaker aurorae than we do, and gas giant planets like Saturn have aurorae that primarily shine in the ultraviolet rather than the visible. Nevertheless, the aurorae are a spectacular sight in the evening, particularly for observers in Alaska, Canada and the Scandinavian countries. But when a solar storm comes our way, keep your eyes towards the north at night; the views will be well worth braving the cold!

Image: Auroral overlays from the IMAGE spacecraft. Image credit: NASA Earth Observatory (Goddard Space Flight Center) / Blue Marble team.

Friday March 13 GAAC Meeting: Cassini and the Moons of Saturn

This month GAAC is fortunate to host Robert Naeye, former Editor in Chief of Sky & Telescope, the world’s most respected and influential popular astronomy magazine. Robert will be speaking to us Friday, March 13, on the Cassini mission to Saturn and its moons.

In July 2004, NASA’s Cassini spacecraft fired its braking rocket and entered orbit around Saturn. Since then, Cassini has orbited the Ring Planet hundreds of times, and returned hundreds of thousands of images, many of which we will see on the 13th, along with a flood of data about Saturn’s magnetic field, particle environment, and ring composition. This enormous dataset has revolutionized science’s understanding of the Saturnian system.

Besides studying Saturn and its rings, Cassini has unveiled its mysterious moons, showing the planet and moons to be a mini-solar system unto itself. In 2005, Cassini deployed the European-built Huygens probe, which parachuted and landed on the surface of Saturn’s largest moon, Titan, arguably the most Earth-like world in the solar system other than Earth itself. Cassini and Huygens have revealed Titan to be a world of complex meteorology and geology, with lakes and rivers fed by methane rainfall.

Perhaps most exciting of all, Cassini has also found jets of water-ice particles laced with organics shooting away from the moon Enceladus, making this small world a potential abode for life. And Cassini images of Iapetus have helped explain how this bizarre moon got its yin-yang appearance, with one side darker than coal and the other as bright as freshly fallen snow.

Robert Naeye earned a master’s degree in science journalism from Boston University in 1992, and later worked on the editorial staffs of Discover and Astronomy magazine. He served as Editor in Chief of Mercury magazine (published by the Astronomical Society of the Pacific) from 2000 to 2003. He worked as a Senior Editor at Sky & Telescope from 2003 to 2007, before moving to NASA’s Goddard Space Flight Center to work as a Senior Science Writer for the Astrophysics Science Division. He returned to Sky & Telescope in June 2008 to serve as Editor in Chief.

Robert is the author of two books: Through the Eyes of Hubble: The Birth, Life, and Violent Death of Stars (Kalmbach, 1997) and Signals from Space: The Chandra X-ray Observatory (Turnstone, 2000). He has contributed to two other books, and has won several awards for his writing and outreach activities.

Our Spring 2015 Series of Public Astronomy Presentations

GAAC February 13 Program Note -- Space Telescopes!

We have an absolute monster of a program for our February GAAC meeting to begin the new GAAC year.

Many of those wonderful pictures of objects in space -- galaxies spinning, black holes feeding, stars being born and dying, planets moving around other stars, and so many others, are taken by a fleet of space telescopes.

We've all heard of the Hubble, but we actually have different space telescopes to observe different parts of the electromagnetic spectrum -- light -- from Gamma rays through our rainbow to the Infrared.

Why are the different space telescopes used and what do we learn from them? What do the different pictures look like? What is the future of space telescopes? We have the answers for you.

On Friday, February 13, North Shore Amateur Astronomy Club president and long-time GAACster Kevin Hocker will show us examples of different space telescopes that do different jobs, and, of course, we'll see some of their amazing discoveries.

The space telescopes we will hear about include:

  • Swift Gamma Ray Burst Telescope
  • Chandra X-Ray Observatory
  • Hubble Space Telescope
  • Kepler - the telescope in the hunt for Earth like planets
  • Spitzer Infrared observatory
  • And of course, the Future of space telescopes - James Webb Space Telescope

Kevin will show us an overview of each telescope, its features, and of course a striking and colorful assortment of their discoveries. Don't miss this one! You'll be telling your friends all about this for weeks!

Sky Object of the Month – February 2015

NGC 1501 – Planetary Nebula in Camelopardalis
by Glenn Chaple


While Go-to technology has gained popularity with backyard astronomers who like to key their telescopes on a sky object with the push of a button, I prefer the no-frills star-hop mode of cosmic travel. Star-hopping lets me see enjoy celestial scenery I’d miss by traveling Go-to. I’ll demonstrate my point with a star-hop to the planetary nebula NGC 1501 in Camelopardalis.

Camelopardalis isn’t very kind to star-hoppers. This sprawling north circumpolar constellation contains just four stars brighter than 5th magnitude. A star-hop to any sky destination in Camelopardalis usually begins with a bright star in an adjacent constellation. To find NGC 1501, we begin at gamma () Persei and trace a 12o path between a pair of 4th magnitude stars to Kemble’s Cascade (refer to the finder charts on the right).Kemble’s Cascade is a stunning 2 ½ o chain comprised of some 20 magnitude 7 to 9 stars.

At its southwest end is the pretty open cluster NGC 1502, punctuated at the center with the eye-pleasing 7th magnitude twins that make up the double star Struve 485. A 1 ½ o push south of NGC 1502 brings us to NGC 1501. Think of it – if we’d traveled to NGC 1501 via Go-to technology, we’d have missed three delightful celestial showpieces!

NGC 1501 is a magnitude 11.5 planetary nebula located about 5000 light-years away. Its slightly oval disk, just under an arc-minute across, can be glimpsed (barely) in a 3-inch scope, but twice that aperture will be needed for a definite sighting.  With a 12-inch scope and dark-sky conditions, you should be able to make out the nebula’s bluish hue and magnitude 14.5 central star.