Tuesday, August 19, 2014

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:

 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.

Monday, August 4, 2014

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.