Wednesday, September 28, 2011

First Astronomy Celebration: Supernovæ

Welcome to Astronomical Events Calendar's first astronomy celebration! After starting in April, 2011 (we've been online since February 2011 but on another site), we start our first astronomy celebration becasue Astronomical Events Calendar has reached 5000 pageviews*! Hopefully we will be doing our next astronomy celebration very soon - at 10000 pageviews, with many more after that to come! Thank you for visiting and I hope you enjoy our first astronomy celebration!

As we begin our first astronomy celebration, have I actually defined what an 'astronomy celebration' is? Here at Astronomical Events Calendar, every time we reach certain goal-points, i.e. every time we reach 5000, 10000, 15000 pageviews +, we post a celebration of our success for making astronomy known (after all that is why Astronomical Events Calendar was created - to promote and inform others about the wonderful world of astronomy!). This celebration's topic is on supernovæ - our festival incorporates all aspects of  what supernovæ are in exciting photodramas and special reports. Again, thank you for your support by visiting, and enjoy the celebration!

*We are at approximately at 5008 pageviews  09/28/2011 @ 04:27:50 pm EST!!


UPERNOVÆ are perhaps one of the most fascinating studying fields of stellar astronomy. When a star is born, it forms in a nebula (literally a 'star nursery'), but when a star dies, it becomes a supernova, going through much molecular change causing a powerful explosion, which gives astronomers much to study. By definition, a supernova is an “exploding star: a catastrophic explosion of a large star in the latter stages of stellar evolution, with a resulting short-lived luminosity from 10 to 100 million times that of the Sun.[1]” Although the definition is loquacious, it does sum in total what a supernova is and provides good insight on the result of an explosion. In a more transparent sense, a supernova is an extremely spontaneous outburst of luminosity and radiation that may (or in lesser cases) may outshine a single host galaxy. But, after approximately a few months or even weeks, the paroxysm ends, resulting in the fading of the star—the star is in the final stages of death, and might outburst again until its foremost death, where it turns into a supernova remnant; a very empyrean and seraphic state. From there, the fate of star is either one of three: to become a neutron star, a black hole, or a white dwarf, each of which are very powerful and exotic celestial phenomena.

The two words ‘supernova’ and ‘nova’ both posses a strong hold on each other’s meanings, but very differently do they translate. From the Latin (novus) for ‘new’, a nova is correctly defined a “star that flares and fades: a star that suddenly increases dramatically in brightness and then fades to its original luminosity over a short period of months or years.[2]” Whereas a nova is a star that periodically emanates radiation and luminosity, a supernova is the stage in which the explosion occurs, letting astronomers known when a star is in the final stages of dying. Although you might think that ‘supernova’ has been in used since the times of Copernicus and Galileo were observing the celestial sphere, it has not. ‘Nova’ has been in use, but Swiss astrophysicist and astronomer Fritz Zwicky first coined the term in 1926[3]. He used the Latin suffix super- translating as ‘more’ or ‘to a farther extent,’ correctly gives us what a supernova really means: a stellar phenomenon greater than a nova. Zwicky was also “the first [person] to understand that [supernovæ] resulted from the explosion of massive stars.[4]

Supernovæ, in astronomy, are events heard and discussed greatly by astronomers, and much is out there to provide us with the invaluable information of what a supernova is and its properties. One of the well-known instruments in space currently is the Chandra X-Ray Observer—a great aid in the discoveries and a great tool to learn more about them. Approximately every fifty years, a supernova occurs within our Galaxy and all the other billions of galaxies in the universe. Many stars die each day just as as many are born. Chandra describes this event as “one of the most violent events in the universe, and the force of the explosion generates a blinding flash of radiation, as well as shock waves analogous to sonic booms.[5]” Although supernovæ seem to be harmless bursts of energy as we here on earth perceive, supernovæ are, as Chandra says, one of the most violent interstellar astronomical phenomena—releasing tons of energy and sonic booms beyond audible comprehension. During an explosion, a single star (called at this point a supernova) can expel much (if not all) of the star’s composition and matter at expeditious rates of up to thirty-thousand kilometers per second, or a tenth the speed of light. From there, a shock wave is driven into the encircling interstellar medium, whereas the ‘interstellar medium’ is the empty space in the universe, not occupied by matter, like stars and planets. After the explosion, the supernova gathers up the expelled mass and brings it back together from the interstellar medium, to create a remnant.

Supernovæ Classification

Based on the knowledge that supernova can explode differently, astronomers have divided them into classes based on their properties and characteristics. But it has not always been this way. Supernovæ were first categorized in 1941 when Rudolph Minkowski realized that more than two different types existed. Although it has been a common error of many people to assume that only two different classes exist[6], it is not true. According to Cosmos, an astronomical encyclopædia written by research astronomers, supernova are “classified based on the presence or absence of certain features in their optical spectra taken near maximum light.[7]” What this means, is astronomers divide supernovæ based on what they are comprised of or lack only during maximum light. In Figure 1, we see the classification of different supernova, which are divided into four ‘types,’ although this fact is well debated (you will see Type Two supernovæ divided into two types, based on light curves they emit.) To explain Figure 1, we see the initials SN eminent on the top; this SN respectively stands for ‘supernova,’ where division starts.

Fig. One in link below.

The H (and no H) beneath ‘supernova (SN)’ stands for ‘hydrogen,’ and ‘no hydrogen,’ specifying whether hydrogen is emitted during the explosion, tell us much about division. Type Two supernovæ will always use hydrogen, ergo as seen in their spectra, meaning, when astronomers view supernovæ, they may look through a different eyepieces to view different things (like infrared filters). Supernovæ with this presence of hydrogen are therefore classified in Type II, whereas where the presence of no hydrogen, is divided into Type I, which can be subdivided from there. The Si is placed in meaning for silicon, or the absence of silicon. If silicon is present (as seen through special filters like hydrogen before), then the supernovæ is a Type Ia, and thus thermonuclear.


[1] Definition provided by the Encarta World English Dictionary, copyright 2009 by Microsoft. Accessed September 27, 2011 from
[2] Ibid. except for link; accessed September 27, 2011 from
[3] Date provided by Merriam and Webster’s Dictionary, copyright 2011 by Mirriam-Webster. Accessed September 27, 2011 from
[4] Fox, Derek. “Fritz Zwicky Advanced X-Ray Astrophysics Facility.” Accessed September 27, 2011 from
[5] Chandra X-Ray Observer, “Supernovæ and Supernovæ Remnants.” The Chandra X-Ray Observatory (November 16, 2010). Accessed September 28, 2011, from
[6] (From comment section). Andrea Thompson, “What is a Supernova?” (May 4, 2009). Accessed September 28, 2011 from
[7] Swinburne University of Technology. “Supernova Classification.” COSMOS—the SAO Encyclopædia of Astronomy. Accessed September 29, 2011 from
[8] Powell, Richard. “The Hertzsprung-Russell Diagram.” Accessed September 30, 2011 from
[9] Hillebrandt, Wolfgang, and Niemeyer, Jens C. “Type Ia Supernova Explosion Models.” Annual Review of Astronomy and Astrophysics 38 (2000): 191–230.
[10] The Astrophysics Spectator. “Thermonuclear Supernovæ.” May 2, 2009; Accessed September 30, 2011 from
[11] Swinburne University of Technology. “Type Ib Supernovæ.” COSMOS—the SAO Encyclopædia of Astronomy Accessed October 1, 2011 from
[12]Swinburne University of Technology. “Type Ic Supernovæ.” COSMOS—the SAO Encyclopædia of Astronomy Accessed October 1, 2011 from

[13] Swinburne University of Technology. “Type II Supernovæ.” COSMOS—the SAO Encyclopædia of Astronomy Accessed October 1, 2011 from
[14] Branch, David & Doggett, Jesse B. A Comparative Study of Supernova Light Curves. The Astronomical Journal—Volume 90, Number 11. November 1985. Accessed October 1, 2011 from
[15] Ibid. Images on page 2304 of study, page 2 in PDF file.

Special Dual-Planet, Bright Star, and Young Moon Conjunction

Tonight, September 28, 2011, two planets, the young moon, and a bright star will all conjunct, giving us a beautiful spectacle of four different objects. As you can see in the picture below, the young moon's crescent faces down towards earth, as Venus (which has returned to the sky!) and Saturn cower below it. The bright star Spica is above them all; earlier this year Spica and Saturn were in conjunction, funny how the objects are really moving now. But you must have special viewing commodities to view this special conjunction. writes:
"However, an unobstructed horizon in the direction of sunset is absolutely essential for witnessing this gathering of phantoms in the twilight. At our mid-northern latitudes, the celestial foursome sets too soon after sunset to be visible."
Although the new moon was yesterday, viewing the crescent will be incredibly difficult, but if you live more southern, you might be able to see more.


Tuesday, September 27, 2011

A Quintet of Saturnian Moons

Although not in transit, eclipse, occultation, or conjunction, these five Saturnian moons have perfectly fit into view of Cassini's camera, allowing us this picture. In the picture from left to right, the moon Janus (179 km across) is farthest left, then Pandora (81 km ac. - orbiting within the A & F ring in middle of image), Enceladus (504 km ac.) in center, Rhea (1,528 km ac. - Saturn's second largest moon), and Mimas (396 kn ac.) far right. NASA writes from the official publication of this picture:
This view looks toward the northern, sunlit side of the rings from just above the ringplane. Rhea is closest to Cassini here. The rings are beyond Rhea and Mimas. Enceladus is beyond the rings. The image was taken in visible green light with the Cassini spacecraft narrow-angle camera on July 29, 2011. The view was acquired at a distance of approximately 1.1 million kilometers (684,000 miles) from Rhea and 1.8 million kilometers (1.1 million miles) from Enceladus. 

Image Credit: NASA/JPL-Caltech/Space Science Institute

Yet, Jupiter's moons are much more acclaimed, Saturn is some competition. Jupiter has (approximately!) 64 confirmed moons. Saturn has 62 moons, although only 53 have been officially named. Astronomers are finding new moons every day, so these numbers will change, hopefully, as astronomers discovers new worlds of learning - after all, every moon is unique and is an individual!

Just for interest - here are the officially named Saturnian moons - funny how they look un-American: Aegaeon, Aegir, Albiorix, Anthe, Atlas, Bebhionn, Bergelmir, Bestla, Calypso, Daphnis, Dione, Enceladus, Epimetheus, Erriapus, Farbauti, Fenrir, Fornjot, Greip, Hati, Helene, Hyperion, Hyrrokkin, Iapetus, Ijiraq, Janus, Jarnsaxa, Kari, Kiviuq, Loge, Methone, Mimas, Mundilfari, Narvi, Paaliaq, Pallene, Pan, Pandora, Phoebe, Polydeuces, Prometheus, Rhea, Siarnaq, Skadi, Skoll, Surtur, Suttung, Tarqeq, Tarvos, Telesto, Tethys, Thrym, Titan and Ymir.

Friday, September 23, 2011

The Beauty of Asteroid 4 Vesta - Let Dawn Bring in the New Multimedia!

As the title implies, Dawn has brought in the multimedia, of photographs, topographical information, animations of rotation, and much more, that is. Can you remember when Vesta was just a small pinprick of light in the night sky (relative to Dawn)? Yes, we have gone a long way on our journey with Vesta - and after the magnificent pictures brought back when Dawn came into orbit, we receive much more, and here they are: Dawn unveiled. But first, let us recap on our journey with Dawn. May 11, 2011, I posted concerning Dawn's first images of Vesta.
A Journey to the Beginning of Our Solar System,’ gracefully rests under the title at the Dawn Mission’s main page at NASA’s Jet Propulsion Laboratory. Explained in an article entitled Dawn: NASA Fact Sheet, that puzzling slogan is interpreted: “Exploring a new frontier, the Dawn mission will journey back in time over 4.5 billion years to the beginning of our Solar is this possible?...thousands of small bodies orbit the Sun [between Mars and Jupiter]...They formed at the same time and in similar environments as the bodies that grew to be the rocky planets (Mercury, Venus, Earth, and Mars). Scientists theorize that the asteroids were budding planets and never given the opportunity to grow...” Although this mission is based on the evolutionist worldview, Dawn will still collect information about these ‘minor planets’ and report back to earth, whether biased or not. Actually, in the article, Dawn: A mission in development forexploration of main belt asteroids Vesta and Ceres, Dawn’s mission is stated clear and more simpler: “Dawn is on development for a mission to explore main belt asteroids in order to yield insights into important questions about the formation and evolution of the solar system.” This sums up everything Dawn will do until the mission is over in 2016, after leaving Ceres. 
Errata for the May 11 Article of Dawn and Vesta: I wrote in the article somewhere that Vesta was the most massive object in the Solar System, NOT! The answer was written in the comment, found here.  In June, correctly June 14, 2011 (approximately a month later), we have about Dawn and Vesta (Dawn is getting closer to Vesta every day now...):
Before starting to orbit Vesta on July 16, Dawn will slow to about seventy-five mph, and "NASA is expecting to release more images on a weekly basis, with more frequent images available once the spacecraft begins collecting science at Vesta," the Dawn mission proclaims. Therefore: you can visit our daily updated page with new pictures and media here.
In July, I did four posts on Vesta (Dawn was approaching closer by now), here are their highlights:
[Vesta's Lunar Possibilities] Only eight more days and counting until Dawn reaches the acclaimed asteroid 4 Vesta! But, let's pause from this excitement and consider the fact that Vesta may house moons. You might ask, 'How can an asteroid have moons?' or 'It's too small to have any gravitational pull strong enough to capture anything.' Well, you are sadly mistaken. We don't know if asteroid 4 Vesta has moons, but an asteroid having moons is quite common...

[The Uniting Date is Set] After predicting the NASA spacecraft Dawn to reach asteroid 4 Vesta on July 16, NASA realized that Dawn will reach its destination earlier than before, (just by a matter of time zones and location). After being launched in September of 2007, NASA has waited almost four years for their beloved spacecraft to reach this forbid world, for the sole purpose of investigating the earliest part of the solar-system's history.

[Dawn Spreads Vesta's Secrets] O beautiful Vesta! Vesta has become quite a spectacular asteroid, not only because of its beauty (as you can see in the image below), but becasue of everything Dawn has sent us so far. After Dawn reached asteroid 4 Vesta this past weekend, continual pictures and information has been sent to our planet. Vesta isn't just any old asteroid.
To present the new pictures of Vesta, and animations brought back (Their source is here - Pictures are updated every day):

Dense Region of Impact Craters
September 23 , 2011
NASA’s Dawn spacecraft obtained this image of the giant asteroid Vesta with its framing camera on Aug. 14 2011. This image was taken through the camera’s clear filter. The image has a resolution of about 260 meters per pixel.
Image Credit: NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA
- Full Image and Caption

 A Full-Frame View of Vesta
A Full-Frame View of Vesta
September 22 , 2011
NASA’s Dawn spacecraft obtained this image with its framing camera on July 24, 2011. This image was taken through the camera’s clear filter.
Image Credit: NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA
- Full Image and Caption

  Young and Old Crater at the Night and Day Boundary on Vesta
Young and Old Crater at the Night and Day Boundary on Vesta
September 21 , 2011
NASA’s Dawn spacecraft obtained this image with its framing camera on August 11, 2011. This image was taken through the camera’s clear filter. The image has a resolution of about 260 meters per pixel.
Image Credit: NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA
- Full Image and Caption


Thursday, September 22, 2011

The Autumnal Equinox: September 23, 2011

The sun will transit the celestial equator September 23, 2011 at approximately 09:04 UT, making the sun transit southward in the northern hemisphere: the start of the autumnal equinox. Derived from the Latin, 'equinox' literally means (aequus + nox) equal night, equinox describes the equality of the night and day, which should be about the same. At this equinox, the sun is at the southern point on the celestial sphere where the celestial equator, at declination zero, and the ecliptic simultaneously intersect. Seasons movie.

Thanks to, the image above shows correctly the September, or autumnal equinox, bringing in autumn. Here, at Astronomical Events Calendar, noting rare and unique phenomena is our passion - how can earth's equinox be shared without other planets'? Thus, here is an image of Saturn (August 11, 2009 by Cassini) at equinox. This is time where light is shown the least, as you can barely see the rings of the planet. Saturn's next equinox will be in 2024, on April 30.

UTC date and time of solstices and equinoxes
year Equinox
day time day time day time day time
2004 20 06:49 21 00:57 22 16:30 21 12:42
2005 20 12:33 21 06:46 22 22:23 21 18:35
2006 20 18:26 21 12:26 23 04:03 22 00:22
2007 21 00:07 21 18:06 23 09:51 22 06:08
2008 20 05:48 20 23:59 22 15:44 21 12:04
2009 20 11:44 21 05:45 22 21:18 21 17:47
2010 20 17:32 21 11:28 23 03:09 21 23:38
2011 20 23:21 21 17:16 23 09:04 22 05:30
2012 20 05:14 20 23:09 22 14:49 21 11:11
2013 20 11:02 21 05:04 22 20:44 21 17:11
2014 20 16:57 21 10:51 23 02:29 21 23:03
2015 20 22:45 21 16:38 23 08:20 22 04:48
2016 20 04:30 20 22:34 22 14:21 21 10:44
2017 20 10:28 21 04:24 22 20:02 21 16:28

Useful Astronomical Calculators: