Moon to Occult Aldebaran

Moon Occulting a Star

Astronomical alignments are special events, times when the motions of the Earth and the rest of the cosmos brings about a particularly interesting juxtaposition of objects in the sky. Today (Sunday 10 April) the waxing crescent Moon will align itself with the bright star Aldebaran, covering it completely for observers in various parts of North America. See this article from Sky & Telescope for a detailed overview of the cities and the exact timing for disappearance and reappearance of Aldebaran.

The Moon sweeps around the entire night sky and touches each constellation of the Zodiac every month, passing in front of hundreds of naked-eye visible stars during its journey. But it is very uncommon for the Moon to pass in front of the brightest stars in the night sky. Aldebaran is a 'first magnitude' star, one of only 22 stars that are at magnitude 1 or brighter (and only four of these are close enough to the Ecliptic to be ever occulted by the Moon: Aldebaran, Antares, Spica and Regulus)
. For that reason the covering and uncovering of a star like this is a dramatic event, worth taking a few minutes with binoculars or a telescope to watch the proper motion of the Moon as a vastly more distant star's light is interrupted by the surface on the edge of the Moon and the light twinkles and vanishes from view for an hour.

On the west coast, the event takes place in broad daylight, but that should not make it any less impressive. Disappearance is at 2:21 pm and reappearance at about 3:40 pm. Check the Sky & Telescope article for more precise timings from around North America.

SkyWeek video - an excellent online astronomy resource

There are many astronomy resources on the web that help you to better understand the night sky. One of the finest is the 5 minute video from Sky & Telescope Magazine entitled SkyWeek. Hosted by associate editor Tony Flanders, I find these weekly videos to be quite illuminating, combining the highlights of the night sky with science and understanding of the things you are seeing. Tony delivers all of this with a great sense of wonder and enthusiasm, without talking down to the audience. I always feel like I am being taught something new and interesting, combining simple observations with deeper astrophysics.

I had the pleasure of spending time with Tony and his family while on an eclipse expedition several years ago, and I really liked how he could balance the far ends of the spectrum of observational astronomy and astrophysics. He has been creating SkyWeek episodes for about one and a half years, and I hope he continues for a long time into the future. The show is carried on many PBS affiliates, adding considerable depth to the quality educational lineup available on public television.

Click here to view.

Comets and Galaxies

One of my primary resources for astronomy information is Sky & Telescope Magazine, and the companion website skyandtelescope.com. I have been a loyal subscriber and follower of this publication for decades, and find the news and information relevant and timely for the amateur astronomer. Two articles recently caught my attention, and I'd like to share them here.

Comets:

Comet Hale Bopp

Astronomers have discovered a comet that in 2013 may become a very major event. Comet C/2012 S1 was discovered last week, and when it comes in close to the Sun in late 2013, could rival Hale-Bopp as a major comet in the night sky. Let's stay tuned for updates on this one. Comets are wonderful and rare, and a bright one like Hale-Bopp was unbelievable, visible from big cities and spectacular from dark locations. I have memories of driving on highway 101 in the San Francisco Bay Area in 1997, looking at a comet through the windshield of my car.

Galaxies:

Hubble eXtreme Deep Field

The Hubble eXtreme Deep Field Observing Team has published a new image revealing 5,500 galaxies, the most distant as old as 13.2 billion years, meaning that it "emitted its photons only 450 million years after the Big Bang." Images like this are not just beautiful, but profound in their richness of information, revealing how far and wide our universe really is, and just how much more there is to discover.

Images courtesy NASA.

Jupiter, Venus and the Moon grace the Evening Sky

The Moon, Venus and Jupiter, the three most dominant objects in the night sky, will form a number of beautiful patters to grace the evening sky in the coming days. Venus and Jupiter have become so dominant in the west after sunset each night that you cannot help but notice them shining like diamonds, and as we enter a new lunar cycle, the young Moon creates beautiful patterns as the daily change in relative position makes for an exciting night sky. Things will get even more exciting next month when Venus and Jupiter reach conjunction, when they are at their closest alignment.

Image courtesy of Sky & Telescope Magazine.

Resources for Urban Astronomers

Over the past years in this blog, I have focused on information and news that can be used by city dwellers, guiding them to find interesting happenings in the night sky that are generally visible in light-polluted skies. I also have focused on San Francisco and West Coast US-based events such as eclipses. In addition to my own posts, I recommend a number of other astronomy sites with helpful information along the same lines, for the casual and amateur astronomer who wants to enjoy the night sky and learn something new about the universe.

Lately, I have been particularly fond of the Astronomy Picture of the Day, always bringing a fantastic new image to light, and the website Spaceweather.com, with interesting news focused on our Sun and the local region of our Solar System with updates on Near Earth Objects. As we approach a solar maximum over the next 18 months, I find Spaceweather.com full of exciting updates about aurorae and sunspots. Sky & Telescope Magazine has been a mainstay for me for years, and the website always includes the latest things to see in the night sky. I often reference images from the Sky & Telescope feature "This Week's Sky at a Glance." And I am enjoying the very interesting posts on the EarthSky blog, such as this great article on "10 Things You May Not Know About Stars."

I hope that you can find a lot of interesting reading and enjoy new perspectives on astronomy. And check in regularly for another post from me (about once a week) with my own musings on the joys of the night sky. I wish you clear skies and happy viewing!

Brilliant Venus

Venus is growing brighter in the west each evening, a brilliant evening 'star' that commands your attention as you see the sunset sky darkening. I enjoy the game of finding Venus right after sunset, particularly from Ocean Beach not far from my home in San Francisco. If you have a good western horizon, Venus is well-placed above and to the left of the point of sunset. I find that just a few minutes after the sun has set, I can often find Venus, knowing that this time of year, the Moon and planets that are in the west shortly after sunset are, in fact, nearly 'above' the Sun since the path of these objects (the Ecliptic) is at a wide angle above the horizon. The image showing the position of the Moon and Venus on January 24, 25 and 26 gives you a sense of how great the angle of the Ecliptic is in the winter.

You can use this concept to help you find Venus after sunset, and see just how many minutes after the sun sets that you can spot that shimmering point of light we call our sister planet.

Image courtesy of Sky & Telescope Magazine.

An Elusive Comet in Urban Skies: Hunting for Hartley 2

Comets can be bold and brash, streaking across the sky like Hale-Bopp in 1997 (see image on right), a comet that was visible even in light-polluted urban areas. Comets can be more humble but then unexpectedly brighten, as did Comet Holmes in 2007. This year marks the return of periodic Comet Hartley 2, a small but frequent visitor to the inner Solar System that is making a fairly close pass to the Earth (11 million miles) on October 20th. Because of the bright Moon on October 20th, this and last week mark the best chances to see the comet because the Moon is young and not brightening the sky. So I took a look last week and again this week to see if I could spot this elusive comet from a city location (last week in a suburb of Frankfurt, Germany and this week from my home in San Francisco).

I hunted quite a while on both occasions, using this very helpful map from Sky and Telescope Magazine. In fact, S&T has been running updates as viewers report seeing Comet Hartley 2 with binoculars. However, it seems that to see Comet Hartley 2 you need a location with very dark skies. I can attest to this, having twice tried and failed to discern the comet from the surrounding stars.

However, all is not lost. Searching for Hartley 2 requires you to find Cassiopeia, Perseus and Auriga, three very nice constellations that grace the Fall and Winter skies. While searching the path of the comet, you encounter a range of deep space objects near and between Cassiopeia and Perseus, and tonight the view was quite good. So even though city lights may have drowned out the faint comet, I enjoyed my first good look at the Double Cluster in Perseus and other celestial gems in the spiral arm of the Milky Way that is beyond Cassiopeia.

I recommend a good jacket, a comfortable chair or blanket, a few minutes patience, the S&T sky map, and binoculars. No matter whether your hunt for Comet Hartley 2 is a success or not, you will be glad you made the effort.

Perseid Meteor Shower 2010

The Perseid Meteor Shower reaches its peak this week and the timing is very good for a fine display of meteors. Every year when the Perseids come around, the biggest concern is the Moon. Its beautiful light is a welcome sight to many, but for amateur astronomers and anyone wishing to see more than a few meteors, moonlight can ruin an otherwise-perfect evening of viewing. This year the Moon is very young during the Perseids and sets not long after sunset, leaving a dark sky for the shower.

The Perseids peak on the nights of Thursday 12th and Friday 13th, with best viewing on Thursday night / Friday morning. You can get detailed information on the Sky and Telescope website or on numerous other web resources.

The best way to see the meteor shower is to find a dark location, give your eyes plenty of time to adapt to the darkness, and be prepared to stay up late (or get up early). Meteor showers are almost always best viewed after midnight when the Earth is powering directly into the meteor stream and the rate increases substantially. The Perseids appear to originate in the constellation Perseus which is in the east after midnight, but that does not mean you have to specifically look east to see the meteors. Lying on a blanket facing directly overhead gives you the most expansive view and you can see meteors coming from the east or passing overhead toward the west. Meteors are wonderful, fast, elusive wonders and you simply need to be warmly dressed, in a place where you can see as much of the sky as possible without light distractions, and patience. I wish you clear skies and a great night or two observing.

A Must See: Four Planets and the Moon

This week the sky features four of the brightest planets in a beautiful lineup in the sunset sky. The illustration on the left, borrowed from Sky & Telescope Magazine, demonstrates how the planets all align themselves in a path across the sky known as the Ecliptic. This line in the sky, actually a gentle curve from west to east across the south part of the sky, is the plane of the Solar System as viewed from our observing platform on Earth. We see fast-moving Mercury close to the Sun, then Venus, Mars and Saturn, a most impressive line-up.

To set this into perspective, the young Moon emerges from the glare of the Sun on Tuesday 13th, moving somewhat parallel to the Ecliptic but each day a bit farther south of the Ecliptic. This is because the orbit of the Moon around the Earth is slightly inclined to the rest of the bodies in the Solar System. And as we just had a Total Solar Eclipse on Sunday, the Moon is following a path away from the Ecliptic into what is called the "descending node" south of the Ecliptic.

I will be talking about this at the California Academy of Sciences at their Nightlife event this Thursday in Golden Gate Park. If you are in or near San Francisco, please join me on the roof for Star Tours!

Geminid Meteor Shower 2009

One of the finest meteor showers of the year is the Geminids, so named because the meteors appear to emanate from the zodiac constellation Gemini. The shower peaks this year on Sunday evening December 13^th and for us on the west coast of the United States, we will be well placed for the peak of the shower at 9:00 pm. Given that there won’t be any moonlight for this meteor shower, conditions are ideal for a good shower that can produce up to 120 meteors per hour in very dark conditions. For those of us who live in urban areas such as San Francisco, we will see considerably fewer meteors. Nonetheless, if you can get yourself away from streetlights, houselights and allow some time to adapt to the dark, you will see some Geminids.

Meteor showers that occur at the same time every year are usually caused by some kind of debris trail that the Earth intersects, showering the upper atmosphere with fine particles in an unusually intense period of time. Based on the way in which the Earth intersects the tiny bits of rock and dust, the meteors will all appear to originate in a single point in the sky, a point known as the "radiant." The Geminid meteor shower appears to originate in the constellation Gemini and as this constellation rises shortly after sunset, this particular meteor shower appears strong all night long, as Gemini treks across the sky from the east nearly directly overhead and then dropping into the west.

NASA has a great website talking about the origins of the Geminids, and Sky & Telescope Magazine has a very helpful article (written by Tony Flanders, an astronomer I've come to know personally) that is full of good tips for seeing the Geminids.

The weather outlook is always a challenge for December, and if the skies are clear they are most assuredly accompanied by a cold evening, so dress extra-warmly for the Geminids and enjoy.

Astronomy Gifts for the Holidays / Telescope Shopping

If you are considering a gift for someone who enjoys astronomy (or want to share something with a young person who might like to discover astronomy), I present to you my astronomy gift guide for the holidays.

A. Astronomy Gifts.

At my local astronomy shop here in San Francisco, Scope City, I asked manager Sam and salesperson Steve what they would recommend for the holidays. Telescopes are plentiful and that warrants a separate section of this blog post - see below. But aside from telescopes, there are binoculars of all types, excellent books, tools such as Star Finders and Planispheres, and new this year, the Sky Scout, a hot selling item from Celestron that has the astronomy hobbyist world abuzz. Point the Sky Scout at an object in the sky and it tells you what the object is and provides additional details. For another approach, you can open a door for astronomy for someone with a gift subscription to Astronomy Magazine or Sky & Telescope Magazine.


B: Telescopes - Top 5 Things to Consider When Buying a Telescope

A telescope is a powerful scientific instrument which, when well cared for, can provide years of viewing pleasure. Top brands include Meade, Orion and Celestron. However, there is a very wide range of options, quality and performance to choose from so before you buy a telescope learn a few things about them. Telescopes.com offers some useful background information, as does Astronomics.com with its informative pages. The Bad Astronomy blog has a helpful article, and this post provides a lot of detail for the telescope shopper. If you summarize all of the articles and if I draw from my own experience, I would recommend five things to think about when purchasing a telescope.

1. Consider Binoculars. They are easy to use, can be used at daytime as well as nighttime, cost less than a telescope, and are a good first test of one's interest in the night sky.

2. Buy quality. Avoid the cheap telescopes at the department stores. They not only have generally poor quality optics, but end up being a turn-off for those who purchase them. It's worth the extra money to get something you will enjoy.

3. Start simple. As much as the high-tech telescopes look like fun, they are still complex instruments that will need some degree of care-and-feeding when you use them. The most basic scopes, simple refractors on a lightweight tripod, take little time to set up and are the most simple to use. Also, a simple telescope is not as bulky and heavy to carry around. For kids, try out the Celestron FirstScope (see below).

4. Be comfortable. You really need to feel at ease with a telescope, so in the best case go to your local astronomy shop and try out a few. Scope City will let you take their binoculars and telescopes out in front of the store and do the "Safeway Test" to see how well you can resolve items in the aisles of Safeway grocery store next door.

5. Learn to use your telescope at your local astronomy club. Amateur astronomers like to help others to learn about astronomy. The San Francisco Amateur Astronomers and San Francisco Sidewalk Astronomers hold Telescope Clinics at their monthly star parties. These are excellent venues to bring your scope and learn to use it with astronomy enthusiasts. Check the Night Sky Network for a club near you.

C: For Young People.

Kids can benefit from astronomy gifts that are easy to use and make it simple to immediately start enjoying. I found numerous websites that showcase books for kids. Skymaps.com has a very well organized list of books for different age ranges, all the way from age 4 to young adult and educator. The Top 10 Astronomy Books for Kids on about.com offers some good choices. On the telescope front in 2009, Celestron premiered the FirstScope, an extremely simple telescope for kids that, from the reviews I've read, is surprisingly good quality yet very low price (about $50 at most outlets). It is an 'official product' of the International Year of Astronomy (IYA) celebration. But in the end I was most enamored with this simple recommendation from the Suite101.com blog:

"What children really need, more than 'stuff,' is for someone to take the time to stand outside with them on a starry night and point out planets and constellations. Teach them the sky. You can give coupons good for '1 Hour of Observing with Mom' or something similar."

Happy Holidays. Stay warm and enjoy the long dark nights.

Total Solar Eclipse in Asia

Today a large part of the eastern hemisphere experienced a solar eclipse, and along a narrow band of Earth viewers were well positioned to experience a Total Solar Eclipse, a rare and beautiful phenomenon. Unfortunately for most, the summer weather was miserable and the skies were cloudy - something that eclipse viewers (and eclipse chasers like me) don't want. Still, there was some limited visibility from a few observing sites. The tour group organized by Sky & Telescope Magazine saw a "murky" total solar eclipse. Better than none, I suppose.

For those of you wishing to see one closer to home, you'll have to wait until 2017 for a Total Solar Eclipse in the USA.