What is a Supernova?

Have you ever seen an especially bright star bursting into view in a corner of the night sky?  If you have been watching the sky for a period of time and wondered why you missed seeing that bright star before, maybe it wasn’t really there. Well, at least not as bright as it now appears.

“What happened,” you ask? That bright star is no longer a star. Most likely it was a red giant star or supergiant red star, depending on its size. That brilliant point of light you now see is the explosion of that star, which has reached the end of its life. Supernovas can temporarily outshine entire galaxies and radiate more energy than our sun in its entire lifetime. Once every fifty years in a galaxy the size of the Milky Way a supernova will occur. To put this in perspective, a supernova happens once every second or so somewhere in the universe.  

This series of events happens when a red giant star has started the nuclear process and has a lot of gravity pulling it inward. The star normally doesn’t collapse inward because there is a lot of nuclear fusion happening inside it; this forces the energy outward. When the fusion stops, the force of gravity pulls the star inward. When the inner shell hits the iron core, a huge shock wave is created, and the star explodes. It has gone supernova. 

Exactly how a star dies depends on its mass. For instance, our sun doesn’t have enough mass to explode as a supernova. That’s good news and bad news for Earth. When our sun does die—in a few billion years—it will swell into a red giant star that will vaporize Earth and all the planets around it. After it destroys most of our solar system it will gradually cool into a white dwarf.

Astronomers have been observing supernovas for quite some time. The Chinese have records dating back to 1054 for one occurring in the constellation we call Taurus. Tycho Brahe and Johannes Kepler observed bright supernovas occurring in the Milky Way Galaxy in 1572 and again in 1604. Today we can see remnants of all three of those supernovas, which appear as expanding clouds of gas where each one was originally discovered.

Although astronomers are observing, studying, and cataloging the occurrences of supernovas, there has not been an occurrence in the Milky Way since 1604. Do you think the Milky Way is due for another occurrence? Are the supergiant red stars, Betelgeuse in Orion (about 600 light years away) and Antares in Scorpius (about 550 light years away) ready to go supernova?  

Visit the Chandra X-Ray Images site for images of some incredible supernovas: http://chandra.harvard.edu/photo/category/snr.html 

My sources: Nasa.gov, Space.com, Science for Kids, Wikipedia.org, Hubblesite.org, Calteh.edu. and national geographic science.

Venus – Earth’s Other Neighbor

Let’s talk about Venus, the second planet from the sun. So exactly how far away is it from the sun? Well, that depends on where it is in its orbit. At perihelion (closest) point it is 66.7 million miles, but at aphelion (farthest) point it is 67.7 million miles away. Remember, everything in our solar system is moving. Each planet rotates on its axis which determines the length of its day. Then each planet rotates in its orbit around the sun, which determines how many days are in its year. Did you know that even the sun itself does a slight rotation in its center position of our solar system?

A year on Venus equals 224.7 Earth days, but the Venusian day stretches on and on. One day on this planet lasts about 243 Earth days. Why do you think that is? If you said because it must rotate very slowly on its axis, then you’re right.

Venus has been referred to as Earth’s sister planet only because of its similar size, gravity, and composition, but unlike Earth, Venus has no moons. The surface of Venus is hard to see because of the reflective clouds of sulfuric acid that surround the planet. Venus has the densest atmosphere of any planet in our solar system. The pressure on the planet’s surface is 90 times greater than that of Earth’s. The probes that have been sent to the surface have collected data but were able to last only a few hours. This is due to the extreme surface temperature reaching 870*F.  

The ancient Egyptians and Greeks thought Venus was actually two separate objects; a morning star and an evening star. Now we know that Venus isn’t a star at all, although it still maintains its nicknames of morning and evening star. When Venus is trailing the sun, it’s at its brightest and comes into view just after the sun sets; it becomes the Evening Star. When Venus leads the sun as it travels across the sky, it will rise in the morning a few hours before the sun; it then becomes the Morning Star. Currently Venus is the Morning Star, rising in the East along the horizon with Jupiter.  

Several joint missions of probes and orbiters have been sent to study Venus since 1961. According to NASA the first was called “Sputnik 7” launched by the USSR in February of 1961. There have been many since then, but recently the “Akatauki” launched by Japan in May, 2010, failed in its mission but will return in 2015. The ESA (European Space Agency) will launch an orbiter named “Bepi Colombo” in July, 2016. This is scheduled as a Mercury orbiter with a fly-by of Venus. A complete mission timeline of probes and orbiters can be found at the NASA site:

http://nssdc.gsfc.nasa.gov/planetary/chronology_venus.html

 We do know that Venus has mountains, valleys and over 1600 volcanoes, many of which are still active. But we don’t know everything about Venus. Did it once have water? Why does Venus have lightning but no rain? Did you know that Friday (Friga and dae) came from the words meaning, “Venus day?”

For additional information and videos, you may also want to visit: http://www.space.com/44-venus-second-planet-from-the-sun-brightest-planet-in-solar-system.html

My sources: Universetoday.com, PlanetFacts.net, Kidsastronomy.com, Solarsystem.nasa.gov, Space.com, en.wikipedia.org/Venus, Planetfacts.net, and randomhistory.com/Venus, and Stardate.com.

The Cassini Mission to Saturn: Alive and Well

Cassini-Huygens is the largest interplanetary spacecraft ever launched by NASA which took place at Kennedy Space Center in Florida on October 15, 1997.  Its mission is to study Saturn and its moons, especially Titan. Almost a seven year journey, it arrived at its destination on July 1, 2004 and has already completed its first mission. Cassini will orbit Saturn at least 76 times in its objective to study five main areas: Saturn’s atmosphere and the interior, the rings, the magnetic environment, icy moons, with a special interest in Titan. It was a group effort by NASA, the European Space Agency (ESA), and the Italian Space Agency.   

So, what is so intriguing about the moon Titan? Well, it’s Saturn’s largest moon and the second largest moon in our solar system, next to Jupiter’s giant moon, Ganymede. The most interesting thing about Titan is that it has an atmosphere, lakes, rivers and dunes, but its bedrock is made of ice as cold as -292F, eroded by rivers of liquid methane. I’m not a chemist, but from what I’ve read in my research, methane and ethane are simple hydrocarbon molecules that can assemble themselves into amazingly complex structures. Titan has both of these elements. Since complex hydrocarbon molecules form the basis of life on Earth could the chemistry on Titan have caused them to cross-over and form some type of life?

Some facts about the Cassini Mission:

·        Cassini traveled 2.175 billion miles on its way to Saturn.

·        It takes about 1hr and 20 minutes for the radio signals to reach Earth.

·        Cassini gets its power from three radioisotope thermoelectric generators (RTG’s) which  consists of a source of heat and a system to convert that heat into electricity.    

·        Saturn is about 75% hydrogen and 25% helium with other trace elements.

·        Saturn’s rings are mostly water ice particles with some rock mixed in.

·        Saturn’s surface gravity is 107% of that of Earth.

·        One day on Saturn is 10.2 Earth hours long. A year is 29.46 Earth years long.

·        Saturn has about 60 moons and counting.

·        Saturn has an interior heat source that produces 87% more energy than the planet absorbs from the sun. Is Saturn still forming (like a star) and using this energy to do so?  

 

The mission was extended in September of 2010 and called the Cassini Equinox Mission. Since the craft is still healthy, scientists have again extended the mission until September 2017. They now call it the Cassini Solstice Mission. This will allow it to continue to study Saturn into its Summer Solstice of May 2017. Hopefully we will find out more interesting facts about Saturn.  

More about the Cassini Solstice Mission at:  http://saturn.jpl.nasa.gov/mission/introduction/

My sources: NASA.gov, European Space Agency, Daily Galaxy, LASP Colorado Outreach Education, and the California Science Center.

PHOBOS AND DEIMOS – MARTIAN MOONS 

There are two small asteroid-like moons that orbit Mars: Phobos and Deimos. Both are named after ancient Greek gods. The larger moon, Phobos, passes across the Martian sky from west to east three times in one Martian day (one sol). On Mars it would appear as half the size of a full moon on Earth. It is so close to the surface that it would not be visible from the Martian poles.

Deimos orbits at about 12,470 miles from the planet and moves slowly from east to west. This moon takes about 30 hours, a little over one Martian sol, to orbit its host. Because of its distance from the planet and the fact that it is only 8 miles across, it appears as a small dot of light in the sky, more like a star than a moon. The surface of this moon is covered with a layer of powdery dust that could be several hundred feet deep. Only the tips of giant boulders can be seen peeking above the dust. Scientists believe the dust formed as a result of billions of years of meteorite impacts. 

Phobos is the larger of the two moons at 14 miles across, and it orbits Mars from only 3,700 miles from the surface of the planet. Phobos is interesting because of its grooves and distinctive crater. It is believed that Phobos survived a powerful impact that may have fractured its interior. The impact may also be responsible for a series of long, deep grooves that appear to radiate away from the crater to an oddly shaped area on the other side of the moon. This impact gouged a large crater which has been named the Stickney crater. Asaph Hall discovered the moons in 1877. He named the crater on Phobos “Stickney,” his wife’s maiden name. He said if it were not for her encouragement he would have given up his search for the Martian moons.

Scientists can only speculate if these moons were born of Mars itself or if they are captured meteors, though the more popular belief is the latter. Much like our Earth moon, both Martian moons always face the same side to the planet. Both moons were named after the sons of Aries, the Greek god to Mars. Phobos means “fear” and Deimos means “dread.” Deimos seems to be slowly spiraling away from the planet while Phobos is drawing closer, which may cause it to collide with the planet in about 50 million years.

I’m wondering: Will Deimos disintegrate and form a ring around Mars before it would collide? Scientists believe there may be water on Phobos; if so, will we create a base on Phobos to store supplies? What do you think will happen?

Visit this link for images of Phobos and Deimos:

http://solarsystem.nasa.gov/planets/profile.cfm?Object=Mars&Display=Sats

My resources are: NASA, Starry Skies, Universe Today, and Space.com

Discover my Lill and Mewe series books about Mars on my website: www.authorjeanelane.com

OORT CLOUD - IS THIS REALLY A CLOUD?     

The Oort Cloud is not really a cloud at all but if we could ‘see’ it from a distance it may have that appearance. It has yet to be observed, the Oort Cloud is a spherical collection of icy objects presumed to exist in the far reaches of the Solar System. It was first suggested by Jan Hendrik Oort in 1950, after his observations of comets. He concluded that comets had the following things in common:

·        Their orbits indicated that they did not originate in interstellar space.

·        They come from all directions – there is no single orbit.

·         Their aphelia (farthest point) tended to group at about 50,000AU (the sun is 1AU from Earth).

Taking all of these observations into consideration and the frequency that they occurred, Oort decided that billions of potential comet material must exist in a spherical shell surrounding the Solar System. Then given their distance from the sun and the weaker gravitational pull, disturbances from objects outside the Solar System could ‘knock’ these icy objects into plunging orbits around the Sun. This would result in the comets we observe.

The Oort Cloud is still generally acknowledged as the origin of the long-period comets, whereas the short-period comets originate from the Kuiper Belt. The Oort Cloud is thought to be an extension of the Kuiper Belt only much larger, containing billions of objects and maybe trillions of small icy objects. Scientists believe that during the planetary formation these objects were left-over debris. They were caught and flung out to the edge of the Solar System by the gravitational pull of Jupiter and Saturn, acting like a sling shot.

Two of the most famous comets, Halley and Swift-Tuttle, possibly higher orbit comets are ones that were pulled into shorter period orbits by the planets. Long period comets, such as Hyakutake and Hale-Bopp can appear at any time and come from any direction, but these two bright comets can usually be seen every 5 to 10 years.

We still have much to learn about the Oort Cloud. To date, scientists believe this region may contain the existence of two Oort Clouds, the inner and the outer clouds. They believe that the objects that reside there formed closer to the sun and were scattered to the outer regions due to gravitational effects. The last theory most commonly accepted is that the Oort Cloud defines the outer most region of our Solar System under the influence of the gravitational pull of our sun.

Let’s take a look – Images and a video:

http://www.space.com/16401-oort-cloud-the-outer-solar-system-s-icy-shell.html

 

My sources: Kids Astronomy, Wikipedia, Solarviews.com, Space.com, European Space Agency, Astronomy/Cosmos, and Universe Today.

THE KUIPER BELT…Where is it?

The Kuiper Belt is a disc-shaped region of icy objects located beyond the orbit of Neptune.  The region was named after a Dutch astronomer, Gerard Kuiper, in 1992. Scientists believe this area is far larger than the rocky asteroid belt that lies between Mars and Jupiter. It is believed this region is 20 to 200 times the size of the Asteroid Belt.

Some known facts about the Kuiper Belt are:

·         The known icy worlds and comets in this region are much smaller than our moon.

·         The Kuiper Belt is a donut shaped ring extending just beyond the orbit of Neptune from about 30 to 55 AU (Astronomical Unit).  The distance from our sun to Earth is 1 AU, or 93 million miles.

·         Short period comets that take less than 200 years to orbit the sun, originate in this region. Long period comets that take more than 200 years, originate in the Oort Cloud, which lies just beyond the Kuiper Belt.

·         There may be hundreds of thousands of icy objects over 62 miles in diameter within the Kuiper Belt.

·         There have been eight identified dwarf planets orbiting within the Kuiper Belt and several of these have tiny moons.

·         The first mission to the Kuiper Belt is New Horizons. New Horizons will reach Pluto in 2015.

·         Gerard Kuiper predicted the existence of such a region in space during the 1950’s. It wasn’t until 1992 his theory was proven correct

Detecting objects in this region of space is not easy because they are very faint and move very slowly. It takes hundreds of years for one of these objects to complete one orbit around the sun.

Later, we have come to realize that Pluto and its five known moons: Charon, Hydra, Nix, P4, discovered by Hubble in 2011, and P5 more recently discovered by Hubble in 2012, reside in the Kuiper Belt.  Pluto isn’t the only dwarf planet to take up residence there, Eris, Makemake, Haumea, Quaoar, Sedna, Orcus, and Varuna orbit in the icy fringes of our solar system.   

The Kuiper Belt is still a busy place. There have been over a thousand objects discovered and it’s theorized that there are as many as one-hundred thousand objects larger than 62 miles in diameter yet to be discovered there.

NASA’s New Horizons spacecraft will reach this region in 2015, and capture the first ever close up pictures of a KuiperBelt object, images of the surface of Pluto.

For more information – check this site out:

New Horizons – now in flight:  http://solarsystem.nasa.gov/missions/profile.cfm?MCode=PKB

My sources: NASA, Windows to the Universe, Wikipedia, Universe Today, and European Space Agency

The Drake Equation

The Drake Equation: The Search for ET

N = R* f_p n_e f_l f_i f_c L   So what the heck is this anyway?  So glad you asked. It’s quite an intriguing formula and has to do with the probability of life existing somewhere “out there.”  In 1961, while working as a radio astronomer at the National Radio Astronomy Observatory in Green Bank, West Virginia Dr. Frank Drake established a scientific formula which became known as the “Drake Equation.” It was actually in 1960 that Drake began his personal search for extraterrestrial intelligence which, shortly afterwards, led to his establishing the SETI institute.

It’s an awesome concept which was put into an equation over 50 years ago. Although Drake made some assumptions to arrive at his equation, you must admit, it’s a great way to help us organize our thinking in the way we search for extraterrestrial life. In 1960 his search was called Project Ozma. As Drake said, “For all we knew, practically every star in the sky had a civilization that’s transmitting.” What he found was that every star is not home to an intelligent, communicative civilization. But even Carl Sagan said that SETI as a science should be pursued.

As we have learned over time, there are many variables with Drake’s formula. The first three quantities are ones we can observe with our current technology. It’s the last four terms where the math gets a little fuzzy. We can say that life is ‘possible’ but not that it actually exists. Scientists today are much more conservative with their estimate and some won’t even speculate. If there is life, what percent of that is intelligent enough to communicate with us? Drake’s answer was 1%. Even that was a guesstimate. Of that 1% what are the chances that it would communicate on a level we could understand?

This may all change, because today we are searching for exoplanets that resemble Earth in size and temperature. Transiting Exoplanet Satellite Survey (TESS) and the James Webb Space Telescope are both due to launch around 2018. They will be looking for Earth-like planets orbiting small stars. Their mission is to concentrate on atmosphere, gases, oxygen, water vapor or other gases that do not belong to ‘dead’ worlds. Sara Seager has revised the Drake equation to focus simply on the presence of any alien life. Her focus is on M stars, the most common. Her calculation suggested that two inhabited planets could be discovered during the next decade. 

N = N*F_QF_HZF_OF_LF_S  This is the Sara Seager equation, a bit different than Drake’s original.
As for me, well I hope that we do find some fascinating, intelligent, and above all, friendly aliens that would be tolerant of us.

For more information on this topic, please visit:

Drake Equation:    http://www.pbs.org/lifebeyondearth/listening/drake.html

Sara Seager:          http://www.centauri-dreams.org/?p=28976

My sources: www.astrociets,org/edu, www.space.com, www.astrobioloblog.wordpress.com