"Science Fiction to Science Fact"

          I found a video about planet Kepler-16b, the first planet that was discovered to orbit two stars. It looks awesome to have two sunrises and two sunsets in a day. Sometimes, fiction is not fiction at all.

Saturn's Rings

Looking at the solar system, what do you notice that is different between the terrestrial planets and the giant planets besides their weights and sizes? That’s right, all the giants planets have rings circling around them. Jupiter, Uranus, Saturn and Neptune, they all have rings. These rings are magnificent and spectacular to look at if you have a decent back yard telescope. They are made of different materials, have different sizes, and color. Saturn’s rings stand out as the most magnificent because of their large size and shape.

Back in 1610, Galileo was able to discover the rings of Saturn using his newly invented telescope. He was the first one to look at the Saturn’s rings but did not know what they were. He called them ears of Saturn as the rings appeared to him as two smaller planets on Saturn’s sides. The discovery had puzzled astronomers for a long time during the time. The launches of NASA’s Voyage 1, Voyage 2 and the Cassini helped us learned about these spectacular rings.

The rings of Saturn are actually a ring system, which is about 1 kilometer in thickness and about 282000 km in size. The ring system consists of billions of particles and the sizes range from tiny dust particle to a km in diameter. The ring system has 5 major rings, G, F, A, B, C, D with G being the farthest and D being the closest from the Planet. The letter name is in the order of which the rings were discovered. Each of these major rings also consists of individual, smaller rings, called ringlets. The gap between ring A and B is called the Cassini Division, which is the largest gap between the rings, about 4700 km. The main element that make up the rings are pure water ice and dust.

We still do not know the origin of these rings exactly. A theory is that these rings formed from the debris of Saturn’s moon that was ripped apart by Saturn’s tidal force. Another theory is that they form from the debris of a disruption of Saturn’s moons.

            The A, B, C rings are called the main rings as they are the largest in size and the most dense. B ring is the most massive of all the rings. The D, G, F rings are fainter and dustier. They are called dusty rings. D ring is the faintest and closest to Saturn.

           

 Reference:

http://en.wikipedia.org/wiki/Rings_of_Saturn

http://pds-rings.seti.org/saturn/

http://csep10.phys.utk.edu/astr161/lect/saturn/rings.html

http://nineplanets.org/saturn.html

Solar Flares

Geomagnetic storms, solar wind, and auroras, are mentioned very frequently recently. These are very interesting and very spectacular to learn about. However, what actually the cause of these phenomena? Solar flares. But what are solar flares?

Solar flares are gigantic bursts of energy from the Sun’s surface. The energy is the magnetic energy that is built up in the solar atmosphere. They release a significant amount of energy, about a sixth of the Sun’s energy lease per second. To the Sun’s scale, it is not much but to the Earth’s scale, energy release is equivalent to 100 millions ton of hydrogen bomb. A typical solar flare can release 10²⁷ ergs per second, equivalent to 10 millions time energy released in a volcano eruption. Solar flares eruption is associated with a Sun’s activity called coronal mass ejection (CME). CME is the process which the Sun ejected streams of very energetic particles. 

Even the flares are very powerful but the vast distance between us and the sun ensures that we will not receive a fireball from the Sun that threatens our planet. However, coronal mass ejection can travel and reach Earth and cause geomagnetic storms that interferes with radio communication, GPS, and satellites. Geomagnetic storms cause the Earth’s magnetic fields to change very quickly.

The Sun is current approaching its maximum in its 11 years cycle, which means that we will have solar flares more frequently. Earlier this month, the Sun erupted with one of the largest solar flares, categorized as X5.4. This solar flare is the second largest flare recorded.

The National Oceanic and Atmospheric Administration categorize the strength and sizes of solar flares in to classes, A, B, C, M, X. A is the weakest class which has a flux of smaller than 10^-7 watt/m². The strength increases 10 fold for each letter. As mentioned above, last week solar flare has X5.4 strength. So we also have X1, X2 and so on, up to X9. X2 is twice X1.  X3 is three times X1.

Sources:

http://en.wikipedia.org/wiki/Solar_flare

http://hesperia.gsfc.nasa.gov/sftheory/flare.htm

http://www.sciencedaily.com/releases/2012/03/120307185105.htm

http://www.sciencedaily.com/releases/2012/01/120125093821.htm

Planets with Two Suns

I don’t watch Star Wars as much as you all do but I do know that Luke Skywalker and Anakin Skywalker’s home planet is Tatooine, a planet in a binary stars system.  I wondered how it feels like to live on a planet with two sunrises and sunsets. It would be awesome to live on a planet like that. Tatooine is just a fictional planet and we can never find Tatooine. Well, we might not see Tatooine but astronomers already discovered a few Tatooine-like planets, planets that have two suns. These planets are called circumbinary planets.

In September 2011, Kepler has discovered and confirmed the first existence of such planets. The planet, called Kepler-16b is only 200 light years from Earth, not a far distance. Unlike Tatooine, the planet is mostly gaseous and not suitable to support life. However, this planet confirm that there is a possibility that a planet can exist in a binary system and given that most stars in the universe is in a binary system, this discover significantly higher the chance of finding a planet that can support life.

Planet Kepler-16b was discovered by studying the transit of the system. They discovered that besides the dips in brightness from primary and secondary eclipses, there was also another dip while the stars were not eclipsing each other. This event hinted that there must a third body in the system. The third body cannot be another star because the gravitational effect is not great that the body must be low mass. Planet Kepler-16b was discovered to be orbiting both stars. Further study confirmed that the planet is about the size of Saturn. Both stars are smaller than our Sun and the planet orbital period is about 225 days.

 Recently, there were two circumbinary planets were discovered. The second planet that is Tatooine-like is call Kepler-34b which has 22% mass and 76%width of Jupiter. The planet is 4900 light years from us and orbit around two sunlike stars. The third planet is called Kepler-35b, about 13% mass and 73% width of Jupiter and about 5400 light years from us.

Astronomer estimated that there are about 1% of binary system can have circumbinary planet orbiting around them, a huge number because there are a lot of binary system out there.

Sources:

http://www.msnbc.msn.com/id/45960242/ns/technology_and_science-space/t/two-new-tatooine- planets-two-suns-discovered/#.T2P7e2JSSg2

http://science.nasa.gov/science-news/science-at-nasa/2011/15sep_doublesuns/

http://www.huffingtonpost.com/2012/01/12/real-life-tatooine-planet_n_1201827.html

Sun's Corona

Corona is the outermost part of the Sun’s atmosphere. Depends on where the Sun is at in its solar cycle, corona can extend millions of kilometers to outer space of the Sun. However, given the massive size of the Sun, it is still a thin layer compared to Earth’s atmosphere to the size of the Earth. Corona is about 1 millions times less bright than the bright photosphere. As a result, we can only observe corona during a solar eclipse or through the use of coronagraph. During eclipse time, corona appears whitish cloud or white crown and the overall shape of corona changes with the sun cycle.

Unlike Earth’s cool atmosphere, corona has temperature of about one million degrees Celsius, much more than the visible part of the Sun, which is only 5800 Kelvin. This is very strange because the outer layer is much hotter than the surface temperature, about 200 times hotter. This can be explained because of the complex magnetic field of the Sun. At this temperature, it emits light at X-ray wavelengths. The spectral lines of corona shows that it contains highly ionized elements, such as iron or calcium. Compare to Earth’s atmosphere, corona is millions less dense.

The shape of corona depends on the where the Sun is in its 11 years solar cycle. At the solar minimum, corona is confined around the equator but at the active time during the solar maximum, corona is evenly distributed at around the Sun. The main features of corona are plumes, helmet streamers, coronal loops, coronal holes.

            We often see helmet streamers during the quiet cycle of the sun. Helmet streamers have loop-like shapes that usually surround the equator of the Sun. Because of the high temperature, corona contains charged particles in plasma state. Sun’s magnetic field thread through the corona and trap these particles in plasma state and make them accumulate over the equator where the magnetic lines are strongest.

Solar plumes are long, thin streamer that extend from the north and the south poles of the Sun. Plume are formed the same way as helmet streamer but at the poles, the magnetic filed are weaker or open which cause the streamer to be thin and less accumulated.

Coronal holes are the dark region of the Sun atmosphere. This region is where there is no charged particle in plasma states accumulate in the Sun atmosphere as a result of open magnetic lines. Coronal holes are often found near the poles of the Sun and this is also the region where solar wind forms.

Coronal loops are the most active of the corona. Coronal loops are usually formed over the active region of the sun where magnetic fields between magnetic regions are strongest.  

References:

http://www.michielb.nl/sun/corona.htm

http://solarscience.msfc.nasa.gov/corona.shtml

http://www.windows2universe.org/sun/atmosphere/streamers.html

http://solarscience.msfc.nasa.gov/feature3.shtml

http://en.wikipedia.org/wiki/Corona

The Sunspot Cycle

The sunspot cycle, which last about 11 years, is an period of increasing and decreasing in the number of sunspots of the Sun. Sunspots, as the name suggests, are the spots on the Sun’s photosphere that appear darker than the surrounding. Sunspots have temperatures about 3000 Kelvin to 4500 Kelvin. Sunspots are the area of the Sun where magnetic activity is very active and intense. They have different shapes and sizes, up to 80000 kilometers and some can be visible from Earth without the aid of a telescope.

The number of sunspots increases and decreases over a period of time with a regular cycle of 11 years. However, each cycle can be from 8 to 14 years. The Sun is most active when the number of sunspots is highest. During the cycle, the frequency of sunspots’ appearance varies by location and time. During a solar maximum, most of the sunspots appear in the middle latitudes of the Sun and move to the equator at solar minimum. The intensity, frequency and locations of sunspots are affected by the Sun’s complex internal magnetic fields that are constantly changing. The Sun’s magnetic poles flip every 11 years.  Because of the constant activity of magnetic fields, a sunspot usually last from a few days to a few weeks and they are dispersed by magnetic pressure.

Sunspots are important for scientists to study the Sun because they are visual indicator of the Sun’s complex magnetic field. Thus, internal structure can be studied. Sunspots are the sites where magnetic fields are powerful and intense. They are the sites where solar many phenomena such as solar flares, coronal mass ejections are from. The sunspot cycle is part of a longer cycle, called the solar cycle, which last about 22 years, which the magnetic poles of the Sun return to original positions.  

Sources:

http://en.wikipedia.org/wiki/Sunspot

http://www.nasa.gov/mission_pages/earth/news/solarcycle-primer.html

http://en.wikipedia.org/wiki/Solar_cycle