Cassiopeia was the Queen of Ethiopia. She is commonly depicted as a lady on a throne, upside down for part of the year. From our latitude (northern Utah), the constellation is circumpolar, meaning that it never sets. It is close enough to the north celestial pole that, if we could hide the Sun, we would see Cassiopeia simply circling the north star over a 24-hour period.

10 pm, MDT, from Salt Lake City, image credit: Starry Night Pro software

It may be difficult to see a lady on a throne in the stars, so I see Cassiopeia as a lazy ‘w’ shape, currently in the northeastern sky at 10 pm, MDT. Using the image below, we can find the ‘w’ shape on its side, about 1/3 of the way up the sky from the northeastern horizon. The distance between the  two end points of the ‘w’ is about 15 degrees. The distance from the bottom of the ‘w’ to Andromeda is also about 15 degrees.

Use the 'w' of Cassiopeia to find M31, the Andromeda Galaxy

M31 is difficult to see from a city or suburb–the darker the sky, the better. Nevertheless, it can be seen without the aid of binoculars or a telescope. This galaxy contains around one trillion stars and is about 5 times the size of our Milky Way galaxy. It is over 2.5 million light years away.

Most of the stars you can see individually in the night sky are all pretty close to us–within a couple thousand light years. The Milky Way, that streak of cloudy light we see across the sky, is a few thousand to a few tens of thousands of light years away. Our entire Milky Way galaxy, containing around 200 billion stars, is probably 100,000 light years across. The Andromeda Galaxy, the nearest major galaxy to us, is over 2.5 million light years away, and there is a lot of nothing between us and it.

Space is a great big empty…

Regardless of the predicted peak hour, the best time to watch for meteors is during the pre-dawn hours (after midnight), your local time, when your position on the Earth is moving into the meteoroid stream. Meteors (commonly called ’shooting stars’ or ‘falling stars’) are actually little more than grains of sand, dust and small pebbles that burn up high in the atmosphere as they fall down to Earth at very fast speeds. The Perseids are traveling at around 60 kilometers per second (130,000 miles per hour!).

Meteor showers are the result of a passing comet. Comets are mountain-sized objects made of frozen gasses, water, and dirt. As the comet approaches and rounds the Sun, it sublimates (turns from a solid directly into a gas, like dry ice), creating a cloudy sphere, called the coma, around the nucleus. The solar wind pushes on the coma forming the long comet’s tail, which always points away from the Sun. It is the gritty particle material of the comet that we see as meteors when the Earth passes through this debris field left behind long after the comet has passed. The comet may not come back for many years, but we will enjoy the meteor shower at about the same time every year. The Perseids are the result of comet Swift-Tuttle, which last passed the Sun in 1993 and won’t be back for another 118 years.

The name ‘Perseids’ comes from the comet Perseus. As you watch Perseid meteors, all over the sky, you can trace backward the familiar streak of light seen. No matter which direction the meteor is headed, the streak of light can be traced backward toward the constellation Perseus. Doing this for several meteors will show that there is a point of convergence for all these backward-traced paths. This point, called the ‘radiant,’ which will be in Perseus.

No need for a telescope or binoculars. Just get comfortable, get out of the city if you can, and enjoy the Perseid meteors this week.

Mercury will be  the most difficult to see, setting a few minutes before 10 pm. It is in Leo at magnitude +0.2.
Venus will be the brightest at magnitude -4, and sets just after 10:30 pm.
Mars sets at about 11 pm, and has a reddish color to it.
Saturn sits atop Mars, and is less than 2 degrees away by the coming weekend.

4 planets at 9:30 pm, MDT, July 30th, 2010

Jupiter rises shortly after 11 pm at a very bright magnitude -2.7. Look for a waning Gibbous Moon 6 degrees from Jupiter on Friday night.

This nice planetary grouping will continue into the next week, but the grouping gets closer and closer to the horizon, making it more difficult to see.

In mid-August a young Moon will join the trio in a spectacular site.

Mercury will be  the most difficult to see, being only about 20 degrees away from the Sun at the beginning of the week, and 23 degrees away from the Sun by end of week. However, it is a bright magnitude 0 object.
Venus will be the brightest at magnitude -4, and will be about 20 degrees away from Mercury throughout the week. Note that Mercury will be about halfway between Venus and the setting Sun.
Mars is about 12 degrees away from Venus, and easily found by noting its reddish color.
Saturn is close to Mars at 5 degrees away, with Mars closing in on Saturn as the days progress. By month’s end, they will be less than 2 degrees apart.

July 23rd, 2010, 9:00 PM MDT

By finding these four planets, one can easily see the ecliptic plane, especially when extended to the Moon over in the southeast this week. The ecliptic is formally defined as the plane generated by Earth’s orbit, or as the path of the Sun across the sky. It is also known as the plane of the solar system, and all major planets and Earth’s Moon are found near the ecliptic.

Beginning June 5, 2010 at 6:45 p.m., “Gateway to the Stars”  will highlight some of the most prominent objects in the night sky each month, using them as examples to teach observing techniques that will help maximize the stargazing experience.

Audiences will learn to navigate using basic techniques involved in stargazing and finding their way around the night sky by becoming familiarized with stars and constellations, planets and other galactic objects visible to the naked eye. Viewers will also learn to explore deep sky objects like double stars, star clusters, nebulas and galaxies to gain insight and perspective on the different components of our universe.

This innovative and interactive experience combines the most recent technology, space imagery and current night sky information to give viewers a truly out of this world experience.  “Gateway to the Stars” begins on Saturday, June 5, at 6:45 p.m.

Tickets for the lecture series are free for Clark Planetarium members. Tickets for the general public are just $1 each or $2 0nline. “Gateway to the Stars” will be featured the first Saturday of every month in the Hansen Dome Theatre at 6:45 p.m.  Additional information and tickets can be found online.

As the May becomes June, the planets will get closer together, Saturn and Mars most notably.  All three will meet up in a beautiful triangle in August.  By the middle of May, a Waxing Crescent Moon will join Venus in the sky.  Over the remainder of the month, it will visit the other two planets as it makes its way towards a Full Moon on May 27, 2010.  Looking to the north, we see the mother bear, Ursa Major, high in the sky.  She protects her cub, Ursa Minor, sitting about half way between her and the northern horizon.

Jupiter and Mercury rule the mornings over the next few weeks.  Mercury will be most visible on the 26th  of May when it is the farthest West of the Sun that it gets to in its orbit.  But the sky will be dominated by brilliant Jupiter, sitting in the southeast at sunrise.  The Moon visits Jupiter on June 6th, and might just barely be visible with Mercury on June 10 th as an extremely thin Waning Crescent.

This time of year is also a great time to go out and look for the Milky Way.  It is a cloudy band of stars that stretches across the sky.  Best visible after midnight, the brightest parts of our galaxy will rise in the southern sky between the constellations of Scorpius and Sagittarius.

Any time of the night, there are wonders to see in the sky.  So, while you are out camping or just standing in your drive way, make sure you look up and see the sights.

The other morning I noticed that, as I’m facing south, Scorpius is nice and bright and easy to spot. Now, according to tradition, I’m ‘a Scorpio,’ but that discussion will have to wait [tease, tease].

Looking south at 6:30 AM, MST, from the Salt Lake valley area

Scorpius is usually thought of as a summer or autumn constellation, when it is visible in the warm, evening skies after sundown. But, the sky we see at night in August is the sky we see pre-dawn in February. And so it is with Scorpius. The familiar fish hook, or ‘J-shape’ of Scorpius is dominated by the bright red star Antares.

Zoomed in view showing Antares and M4

Antares is a respectably bright magnitude +1 star about 600 light years away. Antares is a huge red giant star, so big, in fact, that if it were placed at the center of our solar system, its outer edge would lie about halfway between Mars and Jupiter (in the asteroid belt). Its size is 750 or so times the diameter of our sun, but only 15 times as massive, making Antares a very low-density star. Indications are that this is a star near the end of its life and would probably go supernova in the astronomically-speaker near future. Antares is also very close to the ecliptic.  With it’s brightness, location and brilliant red color, Antares can easily be mistaken for the planet Mars. In fact, the name Antares means ‘like Mars.’ Mars will be approaching Antares later this year (October), but the two will quickly be lost in the sunlight as the Sun passes by Antares in late-November to early-December.

About 1.5 degrees to the right of Antares is a star cluster, M4, known as the ‘Cat’s Eye’ cluster. This cluster is easily visible with binoculars or a small telescope at magnitude +7.5. M4 is only 7200 light years away from us, making it one of the closest clusters to the solar system.

Antares and M4 are due south around 6:30 a.m. right now, and well worth a look.

Solstice means sun stationary. This event marks the time when the sun is at its furthest point south of the celestial equator. The celestial equator is simply a projection of Earth’s equator out into space, and divides the sky into the northern celestial sphere and the southern celestial sphere.

Winter Solstice

The path of the sun against the background stars is called the ecliptic. As the sun moves along the ecliptic, it crosses the celestial equator at the autumnal equinox in September, then gets progressively farther south of the celestial equator until the winter solstice in December. At this point the sun is at its lowest in the sky. The days are short, the nights long, the air is cold. The sun rises well south of east and sets in the southwest. All points on or north of the Arctic Circle experience 24 hours of darkness, with no sunrise or sunset, on the solstice. The North Pole experiences 24 hours of darkness for 6 months, with the winter solstice as the mid-point of that time frame.

Sunrise and Sunset on the Winter Solstice

Many traditional Christmas events, activities and decorations originated in the celebration, fear and/or worship of the sun on this longest night of the year. Evergreen trees all lit up, holly, mistletoe and great fires are all indicative of the yearning to end the declining sunlight and anticipate the eventual return of life to the earth in spring. Though winter is just beginning, and the coldest days are yet to come, the days will slowly lengthen from this point on, as the sun climbs higher and higher in the sky.

In the southern hemisphere the seasons are reversed. The sun is still at its furthest south in the sky, but to those in the southern hemisphere, this means the sun is at its highest point in the sky. Summer is beginning. Antarctica is bathed in 24 hours of sunlight.

There are predictions that observers in Asia may see several hundred meteors around the peak hour. However, under normal conditions, this shower produces 15-20 meteors per hour around peak time, so the best time to look for Leonid meteors would be the pre-dawn hours of Tuesday the 17th.

The shower is named for the constellation of Leo, which contains the radiant.  The radiant of the shower is the perceived origin of the meteors. You can see meteors across the sky, but if you mentally trace backward the familiar streak of light, you will notice that the paths tend to converge within the constellation of Leo.

Meteor showers are the result of the Earth passing through the debris field left behind a passing comet. The Leonids are the result of comet Tempel-Tuttle, which rounds the Sun every 33 years. We are still over 20 years from the next pass, but there is always dust and rocky debris in the path.

No telescope or binoculars are needed. Just dress warm, and watch the skies for Leonid meteors.

This shower could bring up to 60 meteors per hours, but a nearly-full Moon will wash out the dimmer meteors. Still, warming weather makes casual observation for meteors over the next couple of days a comfortable nightime activity.

The Aquarids are named for Aquarius, which doesn’t rise until about 3 a.m.