Uranus and Neptune, the two outermost planets, can sometimes be a challenge to find for the backyard astronomer. But through the coming weeks, Uranus won’t be a challenge at all as it can be found near big, bright Jupiter. At magnitude -2.9, Jupiter dominates the constellation Pisces and stands out clearly in the southern sky. Just look a bit to it’s west, and you’ll find magnitude 5.7 Uranus; currently the closest object to Jupiter of that brightness. Under low magnification, Jupiter and Uranus may (depending on your telescope) be visible in the same field of view. Under high magnification the pale blue disc of Uranus is visible. As the month goes on, the two planets will appear even closer, with Uranus moving to a position more north of Jupiter. If you’ve ever searched the night sky for our solar system’s dimmer planets, that search just got a lot easier. And of course there’s the bonus of Jupiter’s large moons while you’re in the area.
As we move into autumn, the longer nights and still warm weather make this my favorite time of year for astronomy. It’s also a time of year that gives us a wide variety of celestial treats. One of these treats that is often overlooked is the open cluster M52 in Cassiopeia. While not the biggest or brightest cluster, the combination of M52 with brighter nearby stars creates a pleasant arrangement. It also has the benefit of being very easy to find. Simply follow the line formed by the two brightest stars in Cassiopeia for about the same distance as that between the two stars. Getting a good look at M52 will require a somewhat larger telescope, but it is well worth the effort – or it would be if there was all that much effort involved.
We’re just a few days away from the peak of one of the best meteor showers of the year – and the show is already beginning. A few Perseids can be seen throughout almost the whole month of August. But the peak, with 60 meteors an hour or more, comes on August 12-13. And the great news is that, unlike last year, the moon shouldn’t interfere with seeing the peak. So get out there and enjoy the show.
With Jupiter now returning to prime time for viewing (currently rising around midnight) amateur astronomers will be turning their view to this old favorite and it’s four large moons. But with just one glance you’ll notice something has changed. Normally, Jupiter’s two large cloud belts are easily visible through even a modest telescope. But when you look now, you’ll only see one. The South Equatorial Belt began fading late last year, and since May has all but disappeared. This sort of thing has happened before, most recently in 2007 when the belt faded slightly. And in the past the belt has always come back, often making a rather dramatic return. As scientists don’t completely understand the mechanism that causes this, there’s no sure way to know when the belt will be back. But based on precedent, it could be anytime in the next two years. Until then, enjoy a slightly different view of our solar system’s largest planet.
There are a lot of good binary pairs out there, and one of the best is in the often overlooked constellation Delphinus. Gamma Delphini is easily found at the “nose” of this little constellation. It has a magnitude of 4.27 and is about 101 light years away. And it is made up of a yellow-white dwarf star and and orange subgiant. There is speculation that the orange subgiant may harbor a planetary system. So the next time you’re exploring the Summer Triangle, just look a bit to the east for this binary treat.
Tonight the red planet Mars will make a nice pairing with Regulus, the blue-white star that is the brightest in Leo. With Mars currently at magnitude 1.2, it will be similar in brightness to magnitude 1.35 Regulus. While the pairing will be easily visible to the naked eye, a telescopic view will show the color contrast more easily.
When we think of astronomy, we usually think of peering through a telescope at some faint fuzzy out in deep space. But the good news for beginners who may not own a telescope is that some deep sky objects are best seen through a pair of binoculars (which really are just a pair of small telescopes anyway.) One such object is the Coma Star Cluster (officially known as Melotte 111) in Coma Berenices. At a distance of 288 light-years, this open cluster is close enough to cover more than five degrees of sky. With only about 40 stars, it’s not one of the more densely packed clusters. But the good news is that a dozen or so of the stars are bright enough to be seen even from light polluted areas.
Finding the Coma Star Cluster is easy as it lies almost halfway between two bright stars. Start with Denebola, the bright star at the “tail” of Leo, and look toward Cor Caroli. The Coma Star Cluster will be right in between. If you’re not sure which star is Cor Caroli, look toward the end of the Big Dipper’s handle when moving away from Denebola. Cor Caroli will be about two thirds of the way to Alkaid, the star at the end of the handle.
Globular clusters can be among the most beautiful objects in the night sky, and I rarely miss the chance to see one. Well situated for viewing this time of year is M5 in Serpens Caput. With a diameter of roughly 165 light-years, M5 is one of the larger known globular clusters. And at magnitude 5.8, it’s also bright enough to show some nice detail.
Bright Arcturus is a good starting spot for a star-hop to M5. Imagine a line to the southeast to delta Ophiuchus. A little to the side of that line will be alpha Serpens. At around magnitude 2.7, both of these stars are much dimmer than Arcturus, but are still bright enough to be easily found. M5 can be found roughly across the line from alpha Serpens. It’s not one of the more exact star-hops, but it doesn’t need to be. Once you’re in the area, M5 should show up nicely in your finder scope, giving you the chance to enjoy this bit of deep sky beauty.
Every amateur astronomer (or at least those without GoTo scopes) understands the importance of being familiar with the constellations and bright stars of the night sky. These are the signposts that let us “star-hop” our way to faint fuzzies we’re trying to find. One of the most important signposts, high in the night sky at this time of year, is an orange giant star called Arcturus. With a visual magnitude of −0.05, Arcturs is the brightest star in the constellation Boötes and the third brightest star in the night sky. Follow the arc of the Big Dipper’s handle toward the south, and bright Arcturus will be quickly found. Continue following the same arc to the south and you’ll come to Spica, a blue giant, and the brightest star in the constellation Virgo. This path gives rise to the old saying “Arc to Arcturus, then speed on to Spica.” If you’re an experienced amateur astronomer, this path is well known. If you’re just learning, or would like to learn, try to follow the arc tonight and learn two of the main signposts in the night sky.
High in the northern sky, just a little above the handle of the “Big Dipper,” is the grand spiral galaxy M101. As we can see it face-on, M101 is one of several galaxies sometimes called the “Pinwheel Galaxy.” M101 is a large galaxy, nearly twice the size of the Milky Way, and is estimated to be about 27 million light years away. Despite being so large and having a magnitude of 7.86, M101 appears quite diffuse and so isn’t an easy target for smaller telescopes. But if you have dark skies and a nice big Dob, this pinwheel is worth checking out.