News on Saturn

Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. In 1980 and 1981, the Voyager space probes flew by Saturn and measured a day on Saturn as 10 hours and 39 minutes. They also returned the first high resolution images, which revealed a persisting hexagonal wave pattern around the north polar vortex in the atmosphere among other discoveries. The Cassini–Huygens spacecraft arrived in 2004, found the days a little bit longer at 10 hours and 47 minutes. However, a team of planetary scientists at Tel Aviv University in Israel recently reported in Nature that the spin period is 10 hours and 32 minutes and 45 seconds plus or minus 46 seconds for Saturn when the spin was deduced from its gravity field. Their model removed the distortion of the previously measured gravity field that caused the equator of Saturn bulging outward due to Saturn's fast rotations.

Unrelated, NASA is planning a mission to Saturn to explore one of its 61 moons known as Titan. Titan, twice the size of the Earth's moon, is the only moon of Saturn that has an atmosphere. Because the majority of the moon is dominated by methane and ethane lakes in liquid form,  NASA has designed a new submarine that can be operated at -290°F or -179°C  to study the Kraken Mare, the biggest sea on what is Saturn’s biggest moon, at a maximum speed of  2 miles or 3.2 km per hour for a duration of three months.

Postcard US-1575782 from the U.S. was a multi-view card showing the satellites of Saturn.

Lake Okeechobee

Postcard US-3223053 to Switzerland shows a satellite image of Lake Okeechobee in Florida, the second largest freshwater lake contained entirely within the contiguous 48 states in the U.S. Lake Michigan is the largest.

For the largest lakes of the all 50 U.S. States by area including freshwater and saltwater lakes, if the area accounted for the lake includes the area partially in Canada or Mexico, Lake Superior is the largest while Lake Okeechobee ranks tenth.

Okeechobee covers 1,900 square kilometers or 730 sq miles, with an average depth of 3 meters or 9 feet. It is the headwaters of the Everglades wetland ecosystem.

Bern, Switzerland

Postcard CH-214914 from Switzerland shows a satellite image of the city of Bern,  the Bundesstadt or de facto capital of Switzerland. With a population of 137,980 as of 2013, Bern is the 4th most populous city in Switzerland with its metropolitan area of more than  660,000 residents.

The insert on the right shows an aerial view of the historic old town in the center of Bern, on the west of the boundaries of the peninsula surrounded by the River Aare, where the river forms the renowned “Aare loop” and the water temperature never reaches more than 20°C or 68°F. The medieval city center was recognized as a UNESCO Cultural World Heritage Site in 1983.

German Unity Day

Today is the German Unity Day (Tag der Deutschen Einheit), the national day of Germany. Celebrated on October 3 every year, it is a public holiday that commemorates the anniversary of German reunification in 1990. The reunification process started as the Berlin Wall came down on November 9, 1989, and was formally completed on October 3, 1990. The German Unity Day, the national holiday of the Federal Republic of Germany, had been previously celebrated on June 17 since 1954. It was celebrated twice in 1990, once on June 17, 1990 and the other on October 3, 1990.

Postcard DE-1272658  was a lenticular 3D postcard. When viewing from different angles, it shows the reunified Germany by Day or by Night from space. It was also the first official PostCrossing postcard I received from Germany.

Earth Observation from Space

Fifty five years ago, the U.S. satellite Explorer VI was launched by a Thor DM-18 Able III rocket from Cape Canaveral's LC-17A site in Florida on August 7, 1959.  It took the first black-and-white photo of the planet Earth from space, showing a portion of the ocean and the cloud cover over the Central Pacific Ocean. It started an era of the earth observation from space.

Postcard US-1893434 to Russia was one of the six limited edition IKONOS Collector cards from Space Imaging 2003 International Image Festival. It shows the Cathedral of Christ the Saviour on the northern bank of the Moskva River, a few blocks southwest of the Kremlin, in Moscow, Russia. By comparing the image card with the recent satellite image from the same area on Google Maps, you can find out those changes in the area over the past 10 years.

2013 Hurricane Season Starts with GOES 13 Satellite Failure

Hurricane Katrina

I bought this postcard in the gift shop at the CSN Planetarium Observatory, showing the huge Hurricane Katrina looming on the Gulf Coast on August 29, 2005. It devastated New Orleans and other coastal cities with the subsequent failure of the levee system. The image was derived from GEOS-12 satellite's visible wavelength data.

The Atlantic Hurricane Season starts on June 1st and ends on November 30th every year. For 2013, the National Oceanic and Atmospheric Administration (NOAA) projects 13 to 20 named storms with sustained winds of 39 mph or higher, 7 to 11 hurricanes (Category 1 and above) with sustained winds of at least 74 mph, and 3 to 6 major hurricanes (Category 3 and above) with sustained winds of at least 111 mph. The most intense hurricanes (Category 5) have sustained winds at the speed at least 157 mph. Since there are only 12 named storms, 6 hurricanes, and 3 major hurricanes in a regular season, the 2013 season appears to be more active than average.

Hurricane forecasts rely heavily on the Geostationary Operational Environmental Satellite system for data input. However, GOES-13, also known as GOES-East, failed on May 22, 2013. The geosynchronous satellite sits 22,300 miles above the equator at 75°W longitude. It has a clear view of the Atlantic Ocean so it's very valuable to spot early tropical storm activities.

A backup satellite GOES-14 was activated on May 23, 2013. Since it currently remains at its storage position at 105°W, it does not see as far as GOES-13 to the east. It may be moved eastward eventually.

GOES-15, also known as GOES-West, hovers at 135°W longitude. It is responsible for monitoring weather conditions in the western United States and the Pacific Ocean. It remains operational after NOAA briefly expanded its coverage area during the activation of the backup satellite GOES-14.

With severe weather grows more frequently while more people live in the harm's way, it's important to ensure the redundancy of those earth observing satellite systems. However, the next back up satellite is not scheduled to launch until February 2016, subject to further budget and technical delays. There will be real worries in case future satellite troubles cause the gaps for data coverage.