Flyby Night

On the evening of Tuesday, the 8th of November, the asteroid 2005 YU55 will pass fairly close to our Earth, at 202,000 miles. This is actually closer than our own Moon, but will still be a clean pass and represents no threat. Nor, as some have speculated, will it hit the Moon. This visitor will be at its closest at 6:28PM ET, not long after sunset locally. 

Trying to chase the asteroid, though, might be a challenge. It is dark, about the color of asphalt. It is estimated that at its brightest, it will be 11th magnitude, much dimmer than an unaided eye can see; a telescope is needed, and one that is larger than 5 inches in aperture (though seasoned observers can probably go down to 3 inches). If you could see it, though, its movement across the night sky would be amazing, moving very much like a high, slow satellite. 

There are two resources you can use to try to view 2005 YU55. Wikipedia has updated their page on the asteroid, complete with a chart showing its path - 

2005 YU55

Also, Duluth based photoeditor and amateur astronomer Bob King has posted a better chart, complete with times, though you need to keep in mind that he is further north and it is central time - 

Users Guide to Tuesday Night's Flyby

In the meantime, going to try to setup a couple of cameras and hope the weather cooperates. There will be a waxing gibbous Moon, fairly bright, and it could interfere. Still, the opportunity to chase down a rock longer than an aircraft carrier as it zips by, closer than our own Moon, is very tempting.

It's The Great Planet, Charlie Brown!

Halloween this year will see a visit by more than one great, big, spheroid fellow. You may see plenty of jack-o-lanterns this year, but the sky will have a treat of its own. Jupiter will be at opposition on Saturday, 29 October. Opposition means that Jupiter will be "opposite" the Sun; as one sets, the other rises. That means on that night, Jupiter will rise as the Sun slides below the western horizon. After that, Jupiter will rise earlier each evening for the remainder of the year.

So, perhaps Linus was looking for the wrong Great Pumpkin, or at least looking in the wrong patch. Be sure to look for Jupiter as you are out trick-or-treating!

Astronomy Day 2011

In preparation for our local Astronomy Day, 8th October this year, I've decided to re-launch this blog with a little meditation on how to properly celebrate the event. So, without further ado...

10 Things to Do On Astronomy Day

10. Go outside and enjoy the Sun (just don't look at it directly!)

9. During sunset, see how many colors are painted across the sky

8. Look at the Moon (it'll be waxing gibbous this year; that means sort of egg shaped, by the way)

7. Learn the phases of the Moon (like waxing gibbous...)

6. Learn the constellations

5. Make some constellations of your own

4. Look for planets (like Jupiter, which will be high in the eastern sky around 10pm this Astronomy Day; you can't miss it)

3. Learn the names of some of the bright stars (like Aldebaran, Rigel, Altair, Vega and Betelgeuse; bonus points for pronouncing Zubenelgenubi correctly the first time out)

2. Look through a telescope or binoculars, but most importantly...

1. Just look up at that wonderful show in the sky

The Other Stars That Move; Satellites

You may have noticed a very bright star in the western sky these past few weeks, rising slowly and growing brighter. This is the planet Venus, Earth's near twin, and the hottest planet in the Solar System. It will continue rising until it reaches its maximum altitude (or eastern elongation) on the 20th of August. That it's bright goes without saying; its heavy cloud cover reflects most of the visible light that reaches it back into space, and therefore towards us.

Again, it is bright, and will simply grow brighter.
However, there are objects that cross the sky that can be, momentarily, as bright. These are satellites. It so happens that May is a great time to watch for them.
So, just how many satellites are up there, and how many are visible?
The number of satellites that are up there is in the thousands, ranging from a few centimeters or less to the size of locomotives, and one even larger. They look like moving stars; they can be distinguished from aircraft because they are normally just a single point of light. The light they reflect is not always constant, though. As satellites age and go dead, they frequently lose control and begin spinning. When they do this, they appear to pulsate depending upon the speed of their rotation. A few satellites flare up significantly, easily brighter than Venus.
The best time to observe satellites is just after sunset. Satellites can be seen moving either generally from the west to east or due north or south (polar orbits). By the way, be sure to wave at the ones in polar orbits, as many of those are reconnaissance or earth observation satellites, blistering with cameras!
The largest satellite currently in orbit is the International Space Station, the ISS. This orbiting platform covers the area of a football field and has enormous photovoltaic panels (solar panels). There are normally three people on board at any one time; this jumps when a space shuttle is docked.

The ISS in its current configuration. Image courtesy NASA

What does the ISS look like as it passes overhead?
It is brilliant. Its brilliance is already much brighter than Venus, as it slowly follows its arch across the sky. On the 13th of May, it will make a pass through our northern skies here in northeast Florida, rising in the northwest, though much later than most satellites; it will clear the horizon at 10:19pm. The pass will only last three minutes, rising just 15 degrees above the horizon, but if you have a clear shot north, you should be able to see what looks quite a bit like the planet Venus, moving up, growing brighter, then fading through yellow, orange and red as it vanishes into the night.

ISS pass on the 13th of May, 2010. Chart courtesy Heavens-Above.com

The following day, the 14th, space shuttle Atlantis is scheduled to go aloft to the ISS. Try to catch the ISS before the shuttle does!

The Planet & The Bees

For the past few months, the planet Mars has been shining its orange-ish glow furiously in the winter sky, for a time even out-shining the brightest stars. As the months have rolled along, it has begun to dim a bit as the distance between Earth and Mars grows. That doesn't mean that Mars is simply going to fade away; it will still be plenty bright, and it has a rendezvous with a wonderful deep sky object this month. That deep sky object is M44, the Praesepe or Beehive Cluster.

When I say rendezvous, I mean appearing to be very close to. In actuality, there are a few hundred light years between Mars and the Beehive; M44 is 577 light years away.

Mars and M44 on the 13th & 14th of April

The Beehive is an open cluster, a little over a thousand stars gravitationally bound together and sharing a common origin. Most of the stars that compose the cluster are small red dwarfs, too faint to be seen with most telescopes. The ones we do see are much larger and brighter, and, in fact, there are a few giants within the cluster itself. Like most open clusters, the largest members seem to be huddled within the interior, with the fainter stars spreading out from there. It's this arrangement that gives the Beehive Cluster its name, for it really does resemble a swarm of bees buzzing around a hive.

Normally, in urban and suburban skies, the Beehive is a little difficult to locate, due to light pollution. If you do live under such conditions, your best tool for seeing them is either a pair of binoculars or a small telescope. Once it is located, though, the brighter stars immediately show up, and a few more also pop into view with patience. The problem is that the Beehive lies within the somewhat faint constellation of Cancer, so locating it might be difficult. On the nights between the 13th and 16^th of April, 2010, Mars will make finding the cluster much easier, for on its closest approach (16^th April) it will lie 1° 10' north of the cluster. That's approximately two lunar (Moon) diameters. Just find Mars, and head a little way south.

Mars & M44 on the 16th of April

If you live in a more rural region, though, you'll see Mars close to a smudge of light, the condensed light of hundreds of stars that sent their photons in our direction almost fifty years before Columbus set out on his voyage of discovery. Whether you live under urban, suburban or rural skies, be sure to enjoy your voyage of discovery as you get a look at this little gathering of the Planet and the Bees.

When Worlds Appear To Get Real Close

Spend a few minutes outside this evening and take a look to the west just after sunset. You'll see two stars up there in the sky glow. They're not stars, they're planets; Venus and Mercury. And Mercury will not be around for long.
Mercury takes 88 days to go around the Sun; that's about three months. When it reaches its highest point in the western sky (known as its maximum eastern elongation, basically its furthest point east), it doesn't stay long, and begins its dive right back into the sunset. Meantime, Venus takes a leisurely 225 days to orbit the Sun (though, compared to our 365 days, leisurely might not be an appropriate term, but compared to Mercury...). This trip round, Mercury didn't climb quite as high as Venus (it actually reached its peak on the 8th of April).
It's their proximity to one another in the evening sky that probably piqued the interests of astrologers of old; surely, they must have something going on (goddess of beauty seeing the heavenly messenger? Isn't that like having a fling with your postman?). The truth is that they are tens of millions of miles apart, with Venus still climbing to its maximum eastern elongation, which is months away (more next week).


In early July, Mercury will repeat a climb into the west, a good time for it to be caught for sure. If you're a morning person (I am, with the right amount of coffee), you can catch Mercury in early to mid May doing the same thing in the morning sky. Meantime, enjoy catching these two hotties (well, because they are pretty darned hot) as they hang out together in the sunset.

(This post written on a laptop running Xubuntu. Star chart edited from KStars, Solar System chart co-opted from "The Solar System Live" at Fourmilab.ch)

A Comet For Your Perusing

It's named Comet Lulin.
Normally, comets are named after their discoverers (witness Levy-Shoemaker 9 or Hale-Bopp). In the case of Comet Lulin, it is named not after its discoverer but the observatory that took the images; Lulin Observatory in Taiwan (it was actually discovered in 2007 in a series of images by student Quanzhi Ye, a student at Sun Yat-sen University, who was participating in an asteroid survey). This visitor, which literally hails from the depths of space, appears to be making its first visit into the inner Solar System. These comets are of prime interest to astronomers, as they contain material that is essentially pristine and has been preserved for perhaps billions of years. In essence, they provide us a glimpse into the early days of our Solar System.
In the case of Comet Lulin, we have one here that is on such a trajectory that it will pay a brief visit to the inner Solar System (it already had its close encounter with the Sun on the 14th of January) and exit back into deep space, and it's on a no return trajectory. In short, this one probably won't be coming back, at least for tens of millions of years.
As it zips through the Solar System, though, it appears to be heading straight towards us. Considering the tremendous distances in interplanetary space, looks can be deceiving. At its closest, it will pass around 38 million miles (61.2 million kilometers) on the 24th of February, a little more than the distance to the planet Venus.
All of this data is interesting, but for the average person, the bigger question remains - will we be able to see it? Yes, though don't expect a spectacle here. More than likely, even under dark skies, Comet Lulin will be a daunting target, though it will be visible through binoculars and telescopes as a small, fuzzy star. Much talk has been made of the "double tail" that this comet will be producing. This is an illusion, caused by the comet's motion towards us, producing a "spike tail" that appears to be ahead of the comet. What you actually have are two tails, one composed of dust and the other ionized gas. The dust tail is composed of solids, dust, that are being lifted from the surface of the comet. This dust trail has particles that travel at a slower speed compared to the heated gas that composes the ion tail; this tail points almost exactly opposite the Sun. When viewed from above, the tails point in a "V", especially in comets traveling at high speeds. From our perspective here on Earth, it appears as though they are pointed in opposite directions.


Where will Comet Lulin be in the next few weeks? On the 1st of February, it can be found in the morning sky near Libra and the star Zebenelgenubi, but it will begin to move west in our skies until it approaches Saturn and Leo, and moves into the evening sky. On the evening of its closest approach, the 24th of February, it will be just south of Saturn, and it may be possible to view both in the same telescopic view. But that encounter is just one many on its journey. To make finding Comet Lulin easier, below is a list of all the encounters Comet Lulin will have with easy to find objects. The chart also has them labeled.
1 February – East of Zebenelgenubi
16 February – North of Spica
24 February – South of Saturn
1 March – West of Regulus
6 March – South of M44 (Praesepe/Beehive Cluster)
1 April – Between the twins in Gemini


Its speed will be amazing as it moves along from night to night. After that, it will fade away over the weeks until it disappears into the depths, heading into the infinite cold of the outer Solar System and beyond.