Tuesday, March 5, 2013

Europa - Jupiter's "lifeliest" moon


Europa is the smallest of Jupiter’s four Galilean moons. It was discovered by Galileo in 1610. German astronomer Simon Marius also discovered it independently.

Europa has a thin outer layer that is composed of an icy surface with unique linear ridges and cracks. It is relatively smooth compared to other moons that bear large craters due to numerous impacts throughout billions of years.

It is thought to be composed of an iron core, a rocky mantle, and a salt water ocean on its surface, similar to Earth. However, the ocean is much deeper and covers the entire surface of the Moon. Since the moon is so far from the Sun, the ocean is entirely frozen. On the other hand, some scientists argue that there is possibly some liquid water under the thin frozen ice.

Europa is often said to be the moon that is “likeliest to have life” because it is commonly believed by scientists that liquid water oceans possibly lie beneath the thin outer icy layer of surface; and, water, for humankind, has always been an indicator of life, whether it is on Earth or on any place in our solar solar system.

Comparison to Earth’s moon:
It is slightly smaller than Earth’s Moon and its orbit is phased locked around Jupiter, just like the Moon to Earth. This is to say, according to NASA, “the same side of Europa faces Jupiter at all times”. Europa also influences the tides of Jupiter.

















Photograph of Europa taken by Galileo probe (NASA)



















These lines adorn Europa’s icy surface


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Friday, March 1, 2013

Juno - spacecraft probe sent to Jupiter



Juno is a spacecraft probe that was launched on August 5, 2011 and is supposed to arrive in the orbit of Jupiter on July 4, 2016. Juno’s mission is to gather information on the gravitational and magnetic fields of Jupiter. It will also study the “swirling clouds that cover Jupiter’s colorful trademark atmosphere”. Juno is expected to endeavor a five-year journey to Jupiter in which it will attempt to bring to light what the planet is made of and how much water it contains. The spacecraft will use solar panels instead of radioisotope thermoelectric generators to power itself. It is expected to arrive to Jupiter in 2016 and then it “will enter into a low elliptical orbit circling the planet from pole to pole”. The orbit has been strategically planned so that it avoid harmful and deadly belts of charged particles that surround the Jovian planet. Once inside the atmosphere, it will use infrared and microwave instruments to measure the thermal radiation coming from deep within the dense atmosphere. It will also gather data on the gravitational field it has and its polar magnetosphere.

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Tuesday, January 22, 2013

Solar System Post by José del Rosario



            The Discovery News website recently published an article that has become of great interest to astronomers and astronomy aficionados worldwide. The article, titled “Massive Asteroid to Hit Earth in 2040?”, was posted on February 28th 2012 by Leonard David of “space.com”, and as the title implies this article explores the possibility of a 460 feet wide asteroid called “2011 AG5” violently smashing into Earth in 2040. Mount Lemmon Survey astronomers from Tucson, Arizona discovered the giant space rock in January of 2011.

At the moment, scientists are keeping a lookout on this asteroid as to know whether the threat is real or real or not. Some scientists are calling for a deflection plan to prevent a collision between Earth and the asteroid. In the news article, there is a link to an article in “space.com” that clearly states an action plan on how to deflect, or stop, a huge asteroid and prevent it from crashing into our planet.

            The danger this asteroid may pose in future decades was discussed in Vienna, Austria during the past 49th session of the Scientific and Technical Subcommittee of the United Nations Committee on the Peaceful Uses of Outer Space (COPUOS), held in February of 2012. This conferences UN Action Team on near-Earth objects (NEOs) reminded the international community of the various times that this asteroid has come within reach of to Earth and the possibility that it might collide with Earth in the future. However, it is unlikely that this will happen.

             The mass and composition of this asteroid are currently unknown. The asteroid has only been observed for half an orbit so nothing is sure about the calculations that indicate the common path between this asteroid and Earth. In order to declare a “real” threat of the possibility of this asteroid crashing into Earth, the asteroid must be observed for “at least one, if not two, full orbits”, said Detlef Koschny of the European Space Agency’s Solar System Missions Division in Noordwijk, The Netherlands.
           
              Scientists like Koschny are fighting to make other astronomers aware of this asteroid and are trying to create more research institutions like the European Southern Observatory so that they can give objects like this one the allocation of special telescope time that they deserve.
           
              Current studies indicate that, if asteroid 2011 AG5 hits Earth, it will be on February 5th of 20140 and it has a probability of hitting of 1 in 625, or .0016% chance, as denoted by Donald Yeomans, head of the Near-Earth Object Observations Program at NASA’s Jet Propulsion Laboratory in Pasadena, California. Yeoman also said that if the impact probability does not significantly decrease after further observing this object, “there would be time to mount a deflection mission to alter its course.”

The asteroids orbit may be perturbed due to gravitational effects of small regions in space near Earth called keyholes. This implies that the Earth can possibly place the asteroid into path and thus impacting with it due to its own gravitational pull. If the asteroid passes through a keyhole in February 2023, as it is currently expected, it will go closer to Earth and be 0.02 astronomical units (AUs) from Earth. If the asteroid passes through this keyhole, then there is a real chance that it will impact Earth in 20140. The keyhole is roughly 62 miles wide. Yeomans says that it is not that hard to make the asteroid deflect that relatively large keyhole in 2012 and thus prevent the collision expected between 2036 and 2040.

If a collision were to occur, this would definitely mean a great catastrophe for Earth and possibly the end of humankind. It is an currently not an eminent threat; yet, it could become one.

Yeomans said that the current plan is to wait until observations are finished in 2016 so that then they can make any preliminary plans for a potential deflection mission. He says that by 2016 we “will almost certaintly see the impact probability for 2011 AG5 significantly decrease”.
          
            This news is important and pertinent to the study of the Solar System because this event could pose is a potential change to the world we live in and in essence, to the galaxy and the universe we live in. This information contributes to the formation of the Solar System because events like this, collisions between giant asteroids and planets, could have possible changed the course and the structure of the planets in our thirteen billion year old universe. It is definitely an object that should be kept on the lookout but nothing to be scared of, yet.

Artist’s depiction of Earth being hit by an asteroid



Size comparison of Asteroid 2011 AG5 and Earth


References:

For Astronomy II class.