SLOOH Skylog

Like so many of us, Charles Messier became interested in the universe, and especially our galaxy with all its bright celestial objects, as a youngster. (Lucky boy, not much light pollution in his time.) Charles carried this interest forward to become an astronomer in Paris, where, among many other accomplishments, he gained lasting recognition for his catalog of clusters, nebulae, and galaxies. That catalog is the “M” series of heavenly bodies, and it is still in use today.

Interestingly enough, Messier’s first passion was comets (he discovered 20) and yet, his catalog is a meticulously-recorded collection of other important celestial objects. These objects have come to be so well-known, in fact, that they are an integral part of Slooh’s own collection of regularly-featured targets.

Initially, Charles Messier was convinced that the first entry in his catalog, noted as M1, was a comet. But, as the world would eventually learn, M1 was not a comet at all. It is a nebula that evolved from a supernova observed some 950 years ago - or about 700 years before Messier discovered her. (I say “her” because I find this celestial wonder quite beautiful, entrancing, and definitely a bit mysterious.)

M1, the exotic Crab Nebula, was first observed and recorded as an actual supernova by Chinese astronomers in 1054. Additionally, petroglyphs from the Anasazi cliff dwellings in New Mexico and Arizona seem to indicate that they, too, sighted the supernova or, at least, were told about it and recorded it. And although Charles Messier’s independent discovery of the Crab Nebula gets most of the attention, it was actually John Bevis who first discovered and cataloged the object in 1731, twenty-seven years before Messier’s discovery.

Because of the vast distances of space, we witness events long after they actually occur. So, using my handy time/distance calculator and the Chinese year of discovery, I approximate that the M1 supernova occurred around 5000BC or about 6000+ years before the Chinese saw the event. SEDS reports the Crab Nebula’s distance as 6300 light years. You can try calculating this time interval yourself. Click on the time/distance link above to launch the calculator.

Enough history - lets talk about the Crab. First, here she is in all her glory, compliments of Slooh’s Teide 1 High-Mag telescope and the Slooh members.

I selected this image because it shows both the crab-like filaments of the nebula and her mighty pulsar. We will get to the pulsar below, but first some details about the Crab Nebula.

Because it resulted from a supernova (material is moving out and away,) the Crab is ever-expanding at the rate of 1800 km/sec. So, the Crab you view today will not be quite the same when your great-grandchildren view it. Meanwhile, as you look at the image of the nebula, you can, with some imagination, see her resemblance to a crab; but the real source of her name comes from an 1844 drawing by William Parsons, the Third Earl of Rosse. Go ahead and click on the link to see Lord Rosse’s drawing. You can see that it clearly resembles a horseshoe crab - a creature with its own prehistoric lineage.

The Crab Nebula is important for several key reasons. Her traceable history, from her explosive origins to what we see today, provides important data about the evolutionary processes that follow supernova events. Additionally, the 1968 discovery of the Crab Pulsar added another important research element to be studied. In fact, within professional astronomy circles, there is a rumored division between those who study the Crab Nebula and those who do not.

The Crab Pulsar is an amazing and powerful neutron star. Neutron stars evolve from stars that have masses 4 to 8 times greater than our sun. They are the products of supernovas and often remain as part of the remnants. Some neutron stars have fast-moving jets streaming out above their magnetic poles. These jets produce very powerful beams of light that sweep around as the star rotates. These sweeping beams are detected as varying radio frequencies or pulses; thus, we call these stars “radio pulsars.”

Pulsars are found both within and without supernovae remnants. When associated with a remnant, as is the Crab’s pulsar, the nebula is further categorized as a pulsar wind nebula. In fact, scientific data states that the Crab Nebula is much more a pulsar wind nebula than it is a supernova remnant; and because it was the first such object discovered, M1 is the prototype. Of the more than 1600 known radio pulsars, less than 40 are associated with nebulae. In the Slooh image above, you can see the Crab’s pulsar as that fuzzy star-like object directly beneath the nebula’s bright center region.

Fun Facts: * Neutron stars are so dense, just one teaspoonful would weigh one-billion tons on Earth. * The Crab Pulsar contains a mass equal to our sun crammed into an object just twelve miles wide. * The Crab Nebula measures 10 LY across - that’s 58.8 trillion miles or 94.6 trillion kilometers.

I could tell you much more about the Crab Nebula, but I’d rather encourage each of you to dig deeper on your own. You can start by observing the Crab Nebula, either through Slooh’s Editor Channel or by reserving a slot on the Member Channel. The Editor Channel schedule can be found here in the Slooh User Forums, and guidelines for reserving your own Member mission can be found here in the Slooh Help & FAQ. If you need direct assistance, simply pop into the Slooh ChatRoom where you can ask questions in real-time.

As a “Focus On” bonus, we’ll feature the Crab Nebula with a Slooh Mission Alert later this week. We’ll target it through the Slooh telescopes with three back-to-back missions and talk more about it with special commentary on SloohRadio. Watch the Launchpad banner or Slooh Twitter Feed for more details.

NOTE: Currently, a Mission Alert is scheduled for Thursday, Nov. 20, 8:30pm EST / 01:30 UTC - weather permitting.

NOTE: Thursday’s Mission Alert has been rescheduled to Saturday, Nov. 22, 8:30pm EST / 01:30 UTC - weather permitting.

Look up, always, and dark, clear skies for all. And don’t forget to check back next month for another installment of “Focus On.”

For the first time in history, an incoming near-Earth object has been discovered and its impact point known before it reached our planet. Making this feat all the more significant is the object’s small 3m size. Three meters is remarkable. In fact, some would say serendipitous - not the large threat that survey programs seek to discover and yet so small as to underscore the remarkable capability of our “spaceguard” systems.

At the time of its discovery, this incoming object - catalogued as 2008 TC3 - was just 450,000km from our planet and approaching at 12km per second. With less than twenty-fours before “impact”, scientists had to quickly fine-tune trajectory calculations and immediately dispatch notices. And they did it with great success. The calculations were so precise, and the news dispersed so efficiently, that astronomers all across the world were able to track and even photograph the incoming object. More importantly, the information was shared and received responsibly - without inciting panic or prompting end-of-world discourse.

Serendipity turned to good fortune when it was learned that the entry event would occur in a nighttime sky. The object’s small size and likely stony composition meant that it would not survive passage through the Earth’s atmosphere; thus, it would be a sight-and-sound fireball event rather than an actual impact. Of course, fireball events are far more spectacular against a darkened sky. Pilots flying near the expected entry zone - over Northern Sudan, Africa, to be exact - were notified, and at least one pilot did report seeing a bright fireball. However, no actual fireball images are yet known, nor has anyone yet reported hearing the estimated 1.1-2.1 kiloton explosion.

Nonetheless, the approach images are as impressive as any fireball picture. Again, this was a 3-meter object discovered only hours before Earth-entry and traveling at tremendous speed. Photographing it posed a formidable challenge. But that challenge was met with equally striking results. Among the small handful of public images, Slooh achieved the only known non-scientific observatory images and, even more exciting, provided the only real-time observing and imaging opportunity to the non-scientific community.

Although there was little time to prepare, and not every mission was successful, Slooh members did witness the object’s approach just two hours before Earth entry, and a few images even reveal its track across the sky. Again, serendipity played some role. With such short notice, only two random mission slots remained open; and it was exactly those two missions that proved successful. Even those last unsuccessful missions, which had been quickly swapped out for a final attempt just minutes before impact, united the Slooh community in a common passion - that love of space-science and a desire to better understand our universe. Watching the live event provided a very unique opportunity, perhaps even a once-in-a-lifetime experience, for Slooh members.

NEO 2008 TC3 entered the Earth’s atmosphere October 7, at 0243 UTC. It was discovered barely 24-hours earlier, on Monday morning, October 6, by Richard Kowalski of the Catalina Sky Survey team. His discovery was made using Mt. Lemmon’s 60-inch Cassegrain reflector. The Catalina Sky Survey, a NASA-funded project and part of the University of Arizona’s Lunar and Planetary Laboratory, consists of three cooperating surveys utilizing facilities in both Australia and the United States, including the Mt. Lemmon telescope located just north of Tucson, Arizona. The survey is one of several worldwide working toward greater NEO discoveries and better PHA threat assessment.

In this Slooh FITS image, processed by TonyE, we see 2008 TC3’s path revealed as a multi-colored segmented line intersecting a bright background star. This image was acquired 2008Oct07, at 00:43 UTC, exactly 2 hours before entry.

Vulpecula is a small but interesting constellation next to Cygnus. It was invented in 1687 by Johannes Hevelius as “Vulpecula cum Anser” which means, “the fox and the goose.” But, you can imagine what happens when you leave a fox and a goose all by themselves up in the sky… and today we have only the fox, Vulpecula. All that’s left of the goose is the star Alpha Vulpeculae, known as Anser, a very pretty (but faint - 4th mag) red giant.

Vulpecula is home to one of our favorite objects, the Dumbbell Nebula M27. Another interesting member of Vulpecula is Brocchi’s Cluster, also known as “The Coathanger” - possibly an open cluster and possibly just an asterism, but definitely an interesting shape!

We see Vulpecula towards the edge of the Milky Way, so it has a nice collection of open clusters, nebulae, and even a few small galaxies. This constellation is also the location of the first pulsar ever discovered. A pulsar is a rapidly rotating neutron star that flashes a beam of radiation towards us at regular intervals; Vulpecula’s pulsar, PSR B1919+21, flashes a beam of radio waves toward us every 1.3 seconds.

Join us on Monday night September 8 at 9 pm EDT (0100 on Tuesday morning in UT) when the Sky Safari will visit the constellation Vulpecula. And, don’t forget your road map!

Not so long ago, we believed that the Moon was much like our planet. To earth-bound observers, lunar features appeared as great seas and even vegetation-covered plains. Today, of course, we know that quite the opposite is true and that the lunar landscape is not like Earth’s at all.

From Earth, the major features of the Moon’s surface appear simply as lighter and darker regions, but these features are anything but simple. They represent vast basins, sprawling lava plains, and even a few mountain ranges.

Luna’s brighter highlands are riddled with ancient impact craters that can be seen even today. In the darker mares, those impact sites are not so apparent - likely due to flows from hot material during early lunar existence.

One of the most prominent lunar features is Tycho Crater. Visible as a bright ridged circular region near the Moon’s lower limb, and believed to have been formed by a relatively recent impact, this crater has been a target for many telescopes and the subject of much scientific study.

The following slidecast, the first in a series of several featuring the lunar surface, offers a more in-depth look at this fascinating lunar feature.

When we look to the night sky, the one thing that we can be sure to see is stars. Certainly, there are other objects to be seen - distant galaxies, nearby nebulae, maybe a planet or an asteroid - but even each of these would not be seen were it not for the luminous property of stars.

There are many tens of billions of stars in our galaxy. The entire Universe is believed to house more than 70 thousand million million million stars. These stars come in many colors and sizes, all of which tell us something about the stars themselves - their compositions, their expected lifespans and likely manner of death, even whether or not they might host planets.

Stars also come in a variety of groupings - as individuals, as asterisms and constellations, in denser globular clusters, and in younger open clusters. For many observers, open clusters are the prettiest, appearing as a sprinkling of diamonds against a velvety backdrop of the night sky. But for scientists, open clusters offer specific insight into stellar structure and evolution. Their astronomically close distances also enable more accurate calculations of intergalactic distances.

About 1100 open clusters are known within our galaxy, but scientists estimate that there are probably more than 100,000. What are some of those known clusters, and what can they tell us about our solar system, our galaxy, and the Universe? This Saturday evening, at 935pmEDT / 0135 UTC, we’ll target four open clusters with a SLOOH Mission Alert to answer these questions and to explore what makes each of them so special. And for your listening pleasure, we’ll surround the Alert with ambient space music, beginning at 9pmEDT / 0100 UTC.