The Philippine Astronomical Society



planetary geology

Planetary geology, alternatively known as astrogeology or exogeology, is a planetary science discipline concerned with the geology of the celestial bodies such as the planets and their moons, asteroids, comets, and meteorites.
Observing Asteroids and Comets            by Geoff Gaherty, Starry Night Times

I’m often asked when the next comet or asteroid will come along, and my answer surprises many people: There are always quite a few asteroids and comets in the sky, but they are mostly faint and require a telescope or at least binoculars to spot.

By default, Starry Night is set to display these asteroids and comets but, because most are faint, you probably don’t know they’re there unless you turn on their labels (under the Labels menu). Do that right now, and I guarantee that you will be amazed! You will also want to turn the labels off again, as they will drive you crazy.


You will probably never see an asteroid with your naked eye—if you do, it may be the last thing you ever see because that would mean the asteroid was too close for comfort!

Asteroids are very small bodies. Now that Ceres has been promoted to being a dwarf planet, the largest asteroid is Pallas, only 524 km. in diameter, and most asteroids are a lot smaller than that. Since most asteroids are located in the “asteroid belt” between the orbits of Mars and Jupiter, so you have a bunch of very small objects which are very far away. The brightest asteroid, Vesta, just barely reaches naked eye visibility close to its opposition.

Let’s digress for a moment to talk about the “asteroid belt.” This is far from being the sea of rocks you may remember from Star Trek or some computer game. In fact, the asteroids in the “asteroid belt” are so far apart that you would require a telescope and Starry Night to spot one asteroid from the next. Did you know that you can move your observing location in Starry Night from the surface of Earth to any other body in the solar system, or any star, for that matter?

If asteroids are so small and far away, how do we choose which ones to look at? I use the Royal Astronomical Society of Canada’s Observer’s Handbook to find out which asteroids are well placed at the present time. It lists all asteroids brighter than 10th magnitude visible during the year. I use this to compile a shorter list of all asteroids brighter than 9th magnitude.

The largest asteroid, Pallas, will be in opposition on July 29. This is not a very favorable opposition, since Pallas will reach only magnitude 9.5. The good news is that it will take place in an interesting part of the sky, in the tiny but bright constellation of Sagitta, the arrow.

As always, Starry Night will pinpoint Pallas’ location from night to night but, with fast moving objects like asteroids and comets, I like to use Starry Night’s Celestial Path feature to plot its daily motion.

This shows Pallas’ path from June 25 to opposition on July 29, a gently curving arc along the south side of Sagitta.

What will you see? Pallas is so far away that it will appear as a 10th magnitude star. However, it is moving against a rich area of the Milky Way, so even watching it for 10 or 15 minutes should show some motion against the background stars in a telescope at moderate magnification, confirming that this is, in fact, a moving asteroid.

While in the area, be sure to check out the three outstanding deep sky objects: the Coathanger Cluster; the best planetary nebula in the sky, the Dumbbell (Messier 27); and the pretty little globular cluster Messier 71.


As with asteroids, there are always dozens of faint comets scattered all over the sky. However, it’s the occasional bright one that catches our interest. In fact, it was a bright comet, Arend-Roland, that first got me started in astronomy in 1957, and another bright comet, Hale-Bopp, that got me back into astronomy in 1997.

Bright comets are hard to predict in advance, as most are one-time visitors to the inner solar system. There are, however, two interesting comets which will be gracing our skies in the next couple of years.

The First is Comet C/2010 X1 (Elenin) discovered last December by Russian amateur astronomer Leonid Elenin. This comet will make a close approach to Earth, 0.23 au. distant, on 2011 October 16. Present predictions are that it will be just fainter than visible to the naked eye, so binoculars will probably be needed to spot it. It will be sitting right above Mars on October 16 at 6 a.m.

There is a lot of nonsense circulating on the internet about this comet. New age crazies are claiming that it is the mystery planet “Nibiru,” while others say it is a brown dwarf star which will collide with Earth. In fact, it is just an ordinary comet, currently 3 or 4 km. in diameter, which hopefully will sprout a nice little tail around its time of closest approach.

A more interesting comet is expected to put on a spectacular show in a year or two. This is the first major discovery by the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) in Hawaii.

This comet is predicted to reach 0.9 magnitude on 2013 March 25, making it by far the brightest comet in years. It will be low on the western horizon at sunset on that date, but will swing up higher above the Sun over the next few days. This looks like being the first great comet of the 21st century.

Both these comets are currently in the Starry Night comet database, so you can easily track their progress.

Geoff Gaherty

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Quasi Stellar Objects (QSD)                        by  Ma. Angela Lourdes B. Lequiron


Significance of studying and observing quasar

·         It indicates the fate of the Universe.

·         It provides us insights about the composition of early stages of the Universe.

·         It provides new window which gives us an insight into what kind of stars ended the Dark Ages.

·         It is also a velocity indicator.


What is QUASAR?

·         is a short form of QUASI- STELLAR OBJECT (QSO).

·         they are the oldest and most distant objects in the Universe.

·         their very powerful luminosity was said to be due to its SUPERMASSIVE BLACK HOLE who feeds up the accreting materials around it such as gas and dust.


Comparison and Contrast of Quasar with:

 1.     Nebula -A large cloud composed of gas and dust which enables it to manufacture stars and doesn’t have black hole at its center.


2.     SUN  - Is a main sequence star. Its luminosity depends on the nuclear fusion at its center.



·         Composed of gas and dust which allows star formation.

·         It has a black hole at its center but not as massive as the black hole at the center of the quasar.


The Nearest Quasar

Quasar 3C 273 located in the constellation Virgo was the nearest and brightest quasar discovered. Its distance is about 2.44 billion light years away with apparent magnitude of 12.8. And with the distance of 33 light years, it will have its absolute magnitude of -26.7 which means that it will shine out as bright as the Sun at that certain Nebula Galaxies distance. This quasar can be seen with the aid of small telescopes but not with naked eye.


The Farthest Quasar Observable

The most distant known quasar, CFHQS J2329-0301 it is likely billions of light years away and so is seen when the Universe was younger.


Quasar’s Luminosity compared with our Sun, other stars, and galaxies

Quasar is the most luminous object in the Universe. Its luminosity is about one trillion (1012) as the Sun, or about 100 times that of the total light of average giant galaxies like our Milky Way. But the luminosity of quasars appears to declined over time.


Reason for Quasar’s powerful luminosity

The quasars’ powerful luminosity are believed to be powered by a super massive black hole which is 100 million solar masses. The black hole causes the accreting materials to increase their velocity and it also causes friction among particles, thus, they will collide with each other. This collision causes unimaginary amount of heat and energy, this process is the one responsible for making quasars very luminous and allows us to observe them even at their great distance.



Situation # 1:

Assuming you are at the nearby farthest quasar which is at the boundary of the observable universe and provided that Hubble Law holds at that distance (where they are receding more than the speed of light), would you see the object that precede it?


Human’s eye can only perceive manageable speed such as speed of light. If any object is moving faster than the speed of light it is impossible for us to be able to see those objects.

Hubble’s Law

This law states that the distance of various galaxy is directly proportional to its radial velocity. v=Hd



AIn 350 BC, Greek philosopher Aristotle suggested that nature abhors a vacuum, a principle that became known as the horror vacui. Based on this idea that a vacuum could not exist, it was widely held for many centuries that space could not be empty.[2] As late as the seventeenth century, the French philosopher René Descartes argued that the entirety of space must be filled.[3] It became known to Galileo Galilei that air had weight and so was subject to gravity. He also demonstrated that there was an established force that resisted the formation of a vacuum. However, it would remain for his pupil Evangelista Torricelli to create an apparatus that would produce a vacuum. At the time this experiment created a scientific sensation in Europe.

The French mathematician Blaise Pascal reasoned that if the column of mercury was suspended by air then the column ought to be shorter at higher altitude. His brother in law, Florin Périer, repeated the experiment on the Puy-de-Dôme mountain in central France and found that the column was shorter by three inches. This decrease in pressure was further demonstrated by carrying a half-empty balloon up a mountain and watching it gradually inflate, then deflate upon descent. These and other experiments were used to overthrow the principle of horror vacui.[4]

Further work on the physics of the vacuum was performed by Otto von Guericke. He correctly noted that the atmosphere of the Earth surrounds the planet like a shell, with the density gradually declining with altitude. He concluded that there must be a vacuum between the Earth and the Moon.[5]

Early speculations as to the infinite dimension of space was performed in the sixteenth century by the Italian philosopher Giordano Bruno. He extended the Copernican heliocentric cosmology to the concept of an infinite universe that is filled with a substance he called aether, which did not cause resistance to the motions of heavenly bodies.[6] English philosopher William Gilbert arrived at a similar conclusion, arguing that the stars are visible to us only because they are surrounded by a thin aether or a void.[7] This concept of an aether originated with ancient Greek philosophers, including Aristotle, who conceived of it as the medium through which the heavenly bodies moved.[8]

The concept of a universe filled with a luminiferous aether remained in vogue among some scientists up until the twentieth century. This form of aether was viewed as the medium through which light could propagate. In 1887, the Michelson-Morley experiment was carried out as an attempt to detect the Earth's motion through this medium by looking for changes in the speed of light based on the direction of the planet's motion. However, the null result indicated something was wrong with the concept. Since then the idea of the luminiferous aether had essentially been abandoned, to be replaced by Albert Einstein's theory of special relativity. The latter held that the speed of light is a constant in a vacuum, regardless of the observer's motion or frame of reference.[9][10]

The first professional astronomer to support the concept of an infinite universe was the Englishman Thomas Digges in 1576.[11] However, the true scale of the universe remained unknown until the first successful measurement of the distance to a nearby star was performed in 1838 by the German astronomer Friedrich Bessel. He showed that the star 61 Cygni had a parallax of just 0.31 arcseconds (compared to the modern value of 0.287″). This corresponded to a distance of over 10 light years.[12] The distance scale to the Andromeda galaxy was determined in 1923 by American astronomer Edwin Hubble when he measured the brightness of cepheid variables within that galaxy. This established that the Andromeda galaxy, and by extension all galaxies, lay well outside the Milky Way.[13]

The modern concept of outer space is based upon the Big Bang cosmology, which was first proposed in 1931 by the Belgian physicist Georges Lemaître. This theory holds that the observable universe originated from a very compact form that has since undergone continuous expansion. Matter that remained following the initial expansion has since undergone gravitational collapse to create stars, galaxies and other astronomical objects, leaving behind a deep vacuum that forms what is now called outer space.[14]



The term outer space was first recorded by the English poet Lady Emmeline Stuart-Wortley in her poem "The Maiden of Moscow" in 1842,[15] and later popularised in the writings of HG Wells in 1901.[16] The shorter term space is actually older, first used to mean the region beyond Earth's sky in John Milton's Paradise Lost in 1667.[17]

 Source: Wikipedia

Your Age on Other Worlds                                      FB posting by Erika Valdueza  

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