Donald Yeomans

There apparently is a great deal of interest in celestial bodies, and their locations and trajectories at the end of the calendar year 2012. Now, I for one love a good book or movie as much as the next guy. But the stuff flying around through cyberspace, TV and the movies is not based on science. There is even a fake NASA news release out there… So here is the scientific reality on the celestial happenings in the year 2012.

Nibiru, a purported large object headed toward Earth, simply put - does not exist. There is no credible evidence - telescopic or otherwise - for this object’s existence. There is also no evidence of any kind for its gravitational effects upon bodies in our solar system.

I do however like the name Nibiru. If I ever get a pet goldflish (and I just may do that sometime in early 2013), Nibiru will be at the top of my list.

The Mayan calendar does not end in December 2012. Just as the calendar you have on your kitchen wall does not cease to exist after December 31, the Mayan calendar does not cease to exist on December 21, 2012. This date is the end of the Mayan long-count period, but then – just as your calendar begins again on January 1 - another long-count period begins for the Mayan calendar.

On December 16, 1992, 8 days after its encounter with Earth, the Galileo spacecraft looked back from a distance of about 6.2 million kilometers (3.9 million miles) to capture this remarkable view of the Moon in orbit about Earth. Image credit: NASA/JPL
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There are no credible predictions for worrisome astronomical events in 2012. The activity of the sun is cyclical with a period of roughly 11 years and the time of the next solar maximum is predicted to occur about May 2013. However, the Earth routinely experiences these periods of increased solar activity – for eons - without worrisome effects. The Earth’s magnetic field, which deflects charged particles from the sun, does reverse polarity on time scales of about 400,000 years but there is no evidence that a reversal, which takes thousands of years to occur, will begin in 2012. Even if this several thousand year-long magnetic field reversal were to begin, that would not affect the Earth’s rotation nor would it affect the direction of the Earth’s rotation axis… only Superman can do that.

The only important gravitational tugs experienced by the Earth are due to the moon and sun. There are no planetary alignments in the next few decades, Earth will not cross the galactic plane in 2012, and even if these alignments were to occur, their effects on the Earth would be negligible. Each December the Earth and Sun align with the approximate center of the Milky Way Galaxy but that is an annual event of no consequence.

The predictions of doomsday or dramatic changes on December 21, 2012 are all false. Incorrect doomsday predictions have taken place several times in each of the past several centuries. Readers should bear in mind what Carl Sagan noted several years ago; “extraordinary claims require extraordinary evidence.”

For any claims of disaster or dramatic changes in 2012, the burden of proof is on the people making these claims. Where is the science? Where is the evidence? There is none, and all the passionate, persistent and profitable assertions, whether they are made in books, movies, documentaries or over the Internet, cannot change that simple fact. There is no credible evidence for any of the assertions made in support of unusual events taking place in December 2012.

For more information on the silliness surrounding December 2012, see:

• http://www.badastronomy.com/bad/misc/planetx/nutshell.html
• Wikipedia: look under “Nibiru collision.”
• http://www.nasa.gov/topics/earth/features/2012.html

Today, JPL Earth scientist Hui Su joins thousands of other bloggers in more than 130 countries around the world for the Blog Action Day ‘09 Climate Change.

Blog Action Day is an annual event that unites the world’s bloggers in posting about the same issue on the same day, with the aim of sparking discussion around an issue of global importance. The theme of this year’s event, climate change, affects us all and will be the topic of international climate negotiations taking place in Copenhagen, Denmark, this December.

As a world leader in studying Earth’s climate, NASA researchers play a vital role in shaping our understanding of global change. In today’s post, Su discusses the critical role clouds play in climate, and why learning more about them is a key to predicting how our climate will change in the future.

For more information on Blog Action Day, visit: http://www.blogactionday.org .

Hui Su

Clouds are among the most fascinating natural phenomena and have inspired countless works of literature and art. Their ever-changing forms make them a great challenge to atmospheric scientists working to predict how our climate will change in the future in response to increasing greenhouse gases such as carbon dioxide.

Clouds occur at many different heights in our atmosphere and take many different forms. There are three main types of clouds: stratus, cumulus and cirrus. Stratus clouds are low clouds, usually within 2 kilometers (7,000 feet) above the surface. They look like a gray blanket, extending thousands of kilometers across the sky. Cumulus clouds look like puffy cotton balls and extend vertically for large distances. The third type is wispy and feathery-looking cirrus. Cirrus clouds are usually high in the sky, about 7 kilometers (23,000 feet) above the surface. These three types of clouds have different impacts on Earth’s climate due to their unique abilities to reflect sunlight and trap heat radiated from Earth’s surface.

Artist’s concept of NASA’s CloudSat spacecraft, which is providing the first global survey of cloud properties to better understand their effects on both weather and climate. Image credit: NASA/JPL

Su et al. (2008, Journal of Geophysical Research) suggested that cirrus clouds increase as sea surface temperature becomes warmer, further enhancing surface warming. Image credit: NASA/JPL/Caltech
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Stratus clouds can effectively block sunlight from reaching the surface; therefore, they act as an umbrella that cools Earth. Cirrus clouds are relatively transparent to sunlight but can trap terrestrial radiation, JUST AS carbon dioxide does, so they have a net warming effect on Earth. Cumulus clouds can block sunlight and also trap terrestrial radiation. Their net effect varies greatly depending on their actual heights and thicknesses.

Climate scientists have long struggled to quantify how different types of clouds change when global warming occurs. For example, an increase in stratus clouds may cool Earth’s surface, compensating for global warming; while an increase in cirrus clouds may further warm Earth’s surface, exacerbating global warming. Up to now, scientists have not been able to come to a consensus as to whether stratus, cumulus or cirrus clouds will increase or decrease as global temperatures increase.

A key advancement in cloud studies in recent years has been the availability of global satellite observations of clouds, especially the measurements of clouds at different heights provided by NASA satellites like CloudSat, managed by NASA’s Jet Propulsion Laboratory (JPL). These observations are allowing scientists to better simulate clouds in climate models, which are the primary tools climate scientists use to predict future climate change. Up till now, the dynamic nature of clouds has made them very difficult to simulate in current climate models. But by applying space data, we at JPL are working closely with modelers to improve cloud simulations and thereby improve predictions of future climate change.

To learn more about JPL’s research in this field and the CloudSat mission, visit:
http://cloudsat.atmos.colostate.edu/home .

Bjorn Lambrigtsen

JPL scientist Bjorn Lambrigtsen goes on hurricane watch every June. He is part of a large effort to track hurricanes and understand what powers them. Lambrigtsen specializes in the field of microwave instruments, which fly aboard research planes and spacecraft, penetrating through thick clouds to see the heart of a hurricane.

While scientists are adept at predicting where these powerful storms will hit land, there are crucial aspects they still need to wrench from these potentially killer storms.

Here are thoughts and factoids from Lambrigtsen in the field of hurricane research.

1. Pinpointing the moment of birth

Hurricane Gustav moved along the southern side of Jamaica on Aug. 29, 2008. Image credit: NASA MODIS Rapid Response

Most Atlantic hurricanes start as a collection of thunderstorms off the coast of Africa. These storm clusters move across the Atlantic, ending up in the Caribbean, Gulf of Mexico or Central America. While only one in 10 of these clusters evolve into hurricanes, scientists do not yet know what triggers this powerful transformation.

Pinpointing a hurricane’s origin will be a major goal of a joint field campaign in 2010 between NASA and the National Oceanic and Atmospheric Administration (NOAA).

2. Predicting intensity

Another focus of next year’s research campaign will be learning how to better predict a storm’s intensity. It is difficult for emergency personnel and the public to gauge storm preparations when they don’t know if the storm will be mild or one with tremendous force. NASA’s uncrewed Global Hawk will be added to the 2010 research armada. This drone airplane, which can fly for 30 straight hours, will provide an unprecedented long-duration view of hurricanes in action, giving a window into what fuels storm intensity.

3. Deadly force raining down

Think about a hurricane. You imagine high, gusting winds and pounding waves. However, one of the deadliest hurricanes in recent history was one that parked itself over Central America in October 1998 and dumped torrential rain. Even with diminished winds, rain from Hurricane Mitch reached a rate of more than 4 inches per hour. This caused catastrophic floods and landslides throughout the region.

4. Replenishing “spring”

Even though hurricanes can wreak havoc, they also carry out the important task of replenishing the freshwater supply along the Florida and southeastern U.S. coast and Gulf of Mexico. The freshwater deposited is good for the fish and the ecological environment.

5. One size doesn’t fit all

Hurricanes come in a huge a variety of sizes. Massive ones can cover the entire Gulf of Mexico (about 1,000 miles across), while others are just as deadly at only 100 miles across. This is a mystery scientists are still trying to unravel.

NASA and NOAA conduct joint field campaigns to study hurricanes. The agencies use research planes to fly through and above hurricanes, and scientists collect data from NASA spacecraft that fly overhead. NOAA, along with its National Hurricane Center, is the U.S. government agency tasked with hurricane forecasting.

For more information on how NASA and JPL study hurricanes, go to www.nasa.gov/hurricane and http://tropicalcyclone.jpl.nasa.gov