Seeing the Milky Way in City Skies

Summers bring pleasant viewing and a wealth of richness in the heavens. As the Summer Triangle rises and dominates the night sky, two of my favorite Zodiac constellations, Scorpius and Sagittarius, are visible deep in the southern sky. These big, bold constellations combine with the Summer Triangle to guide the urban star-gazer to the Milky Way.

For anyone who has seen the spectacle of the Milky Way in dark skies, you know just how profound this band of light looks as we view our own galaxy from within. And I know how disappointing it is after a few days in dark skies, to return to the city and realize that the beauty of the Milky Way is missing. But don't despair, for even in urban settings, you can still see many of the wonders of the Milky Way. To do this, you need to use a telescope or binoculars. Using Scorpius and Sagittarius as your anchor on the southern horizon, and the Summer Triangle high above, point the telescope or binoculars into the sky and move slowly from the south slowly overhead. You are looking into the Milky Way, and with the magnification and light-gathering of a telescope or binoculars, you cut through the glow of the city lights and enhance the light from space. And that will be a rewarding moment under the sky. No need for a fancy star chart or an iPhone app. All you need is a sense of wonder and a comfortable chair.

Perseid Meteor Shower 2011

Every Summer, the Perseid Meteor Shower raises the hopes of those interested in the night sky. Being one of the biggest meteor showers of the year, coupled with the fact that it takes place in the middle of Summer, it's not surprising that many look forward to it. However, some of the best viewing of the Perseid Meteor Shower in 2011 will be washed out by the Full Moon which coincides with the peak of the shower on August 12th and 13th.

However, all is not lost. Meteor showers vary in the duration, some lasting only a day or two with a clear peak moment, while others are spread over a longer period of time. Luckily, the Perseids are a longer-duration meteor shower, starting in late July and continuing through mid-August. Although the best viewing is on August 13th, the rate of meteors is already dramatically increasing by August 9th, and at that point in time this year, the Moon will not completely wash away the meteors. In fact, the Moon will be setting in the early morning, giving the dedicated meteor chaser an hour or two to see some fine Perseids before the first light of dawn. So my advice is to look on this schedule:

Early morning Tuesday August 9th: From 1:30 until 5:00 am.

Early morning Wednesday August 10th: From 2:30 until 5:00 am.

Early morning Thursday August 11th: From 3:30 until 5:00 am.

Early morning Friday August 12th: From 4:30 to 5:00 am.

These times are for San Francisco. The start time depends upon when the Moon sets, a bit later each morning. The end time depends upon the time of your local sunrise which may vary based upon your location. Use this website to determine your local conditions. In San Francisco, sunrise is shortly after 6:00 am, so I recommend viewing until 5:00 am at which time the first light of dawn will begin to interfere with viewing of meteors.

As is the case with every meteor shower, you need to get yourself in as dark a location as you can. In a big city, that means away from streetlights and in a spot with a big view of the sky. The meteors will appear to emanate from the East, but they will cross the sky in all directions, so your best view is lying on your back looking up. Get some blankets, stay warm and enjoy.

Image courtesy National Geographic.

Daytime Astronomy: Sunspots

Summer nights are short, making it more challenging to enjoy the night sky. But days are long, and the Sun often provides some fireworks to make things interesting. Right now, the Sun is moving into a period of maximum solar activity. Maximum solar activity comes as part of an 11 year cycle in which we observe peaks and valleys in the number and size of Sunspots, with the next peak in 2012.

Sunspots are areas on the surface of the Sun where magnetic fields have caused a disturbance in the normal flow of heat from the core of the Sun , and the areas appear black through Earth-based solar telescopes. These areas are "cooler" than the surrounding surface of the Sun (I'm not sure if the term "cooler" applies to the surface of a 10,000 degree star!), which means that Sunspots check in at about 5000 degrees. With a well filtered telescope, the areas look black by contrast to the extremely bright solar surface, known as the Photosphere. It's one of nature's truly fascinating phenomenon, and a wonderful thing to see directly through a telescope.

Our eyes are sensitive light sensors, and are completely overwhelmed when you look directly at the Sun. The heat from the intense radiation of the Sun can cause blindness in a matter of seconds. Fortunately we instinctly look away from the Sun and preserve our vision naturally. Experienced astronomers, however, can safely use solar filters on telescopes to cut the brightness of the Sun to the brightness of the Full Moon, and hence use a standard telescope with a filter to enable daytime astronomy. In San Francisco, you sometimes find a Sidewalk Astronomer showing off the Sun during the day. With the increase in Sunspots during 2011 and into 2012, I'll be out on the sidewalk doing this from time to time, and even if you don't have access to a solar telescope, you can check out Sunspots on the solar surface daily at the excellent website SpaceWeather.com. This website has some very amazing images of the Sun and other space-related "weather" items.

Remember: only view the Sun with properly designed filtering intended for safe solar viewing.

Image courtesy of SpaceWeather.com.

One Year on Neptune

We passed a landmark moment this month, the one-year anniversary of the discovery of the Blue Planet, Neptune -- one Neptunian-year, that is, which is 165 of our Earth-years. This gem of a planet is something that an urban astronomer has to work a bit harder to see, but once spotted it is a lovely blue point of light in the sky, a fine payoff for those with the persistence to track it down against the backdrop of stars in the heavens.

During its long trek around the Solar System, Neptune has periodic close encounters with other planets, as it did during the "Triple Conjunction of 2009" with Jupiter. However, this year it stands alone in the constellation Aquarius, more challenging to find because we don't get Jupiter as a beacon leading us to find the elusive blue planet. However, using this star chart, a pair of binoculars, a dark backyard location, and some patience, I am sure you can find it. I will be looking from time to time over the coming months as Neptune moves from the morning sky into the evening sky, scanning for its dim blue glow in the vastness of the night sky.

KFOG Podcast - July 8, 2011

Today was the final launch of the Space Shuttle. KFOG's Irish Greg and I talk about this historic event, about the wonders of the Summer night sky, and about upcoming Star Parties in the San Francisco Bay Area. All in 5 minutes! Listen here.

Moon in Descent

The Moon traces out a path across the sky that is slightly offset from the path of the planets and Sun (the well-known "ecliptic" path). The orbit of the Moon is inclined to the ecliptic by 6 degrees, meaning that at any given point in a month, the Moon might be found in the sky just at the ecliptic, or moving below the ecliptic (up to 6 degrees away from it), or above the ecliptic. As it travels in its 29 day journey around the Earth, the Moon passes through the ecliptic twice, once going down (descending node) and once going up (ascending node).

Since we just finished an Eclipse Season, the Moon's nodes are very near to the points in space where we have New Moon and Full Moon, enough that from the New Moon a few days ago, to the First Quarter Moon later this week, we see the Moon traveling past the descending node and moving well below the ecliptic. Visual proof of that this week comes in the form of Saturn and Spica (see image), both of which are nearly on the ecliptic. The daily change in location of the Moon shows us just where the Moon is in relation to the ecliptic, this week skirting just south (below) this imaginary line in space.

The Moon amid planets and star clusters

The morning sky this week will be rich with easy-to-spot celestial objects in the hour before sunrise. Find a good view toward the eastern horizon and use binoculars to enhance the view of Venus, Mars, the waning crescent Moon and two of the finest star clusters in the sky, the Pleiades and Hyades. I am looking forward to it!

Get Involved: Public Nights at Observatories, Stargazing at the Libraries and Museums

There are many ways to get involved with astronomy, and I want to provide some links to get you going places.

First, some places where I present astronomy. I am a regular at the California Academy of Sciences most Thursdays at their NightLife event. These are for adults-only (sorry, kids, they serve alcoholic beverages), and when the skies are clear, they have astronomers with telescopes trained on stars and planets, and me giving tours of the night sky. Stop by on a Thursday night and enjoy the Cal Academy, and journey up to the Living Roof for a personal tour from me.

I make special presentations for organizations around the Bay Area, this week at the Marina Public Library as part of the IMBIBE series of events being put on by the Friends of the San Francisco Public Library. Come join me Friday night, June 17th, to see our nearest star (with its fascinating Sunspots) up close, and when the skies turn dark, a close up view of other celestial highlights.

Local observatories and science museums hold regular astronomical viewing nearly every weekend. Chabot Space and Science Center has viewing on Friday and Saturday nights through their powerful telescopes. The Peninsula Astronomical Society hosts viewing at the Foothill College Observatory in Los Altos Friday nights. And the Lawrence Hall of Science has viewing on Saturdays. Finally, my own club, the San Francisco Amateur Astronomers, hosts a monthly Star Party at Mt. Tam in Marin, along with a lecture at the Mountain Theater. I often give tours of the night sky at the Mt. Tam star parties.

There's no excuse if you live in the Bay Area. And if you are not in the San Francisco Bay Area, check the Night Sky Network to find a club and activities near you.