Questions answered

QUESTION: Earth Watch reported, “The cyclical phenomenon also caused 2008 to be cooler than any year so far this century, according to the World Meteorological Organization.” I can understand minor deviations, but how can this substantial decrease and record cold temperature in 2008 be possible, since elevated CO2 and the industrial revolution is the root cause of global warming?

– Doug Austin,
Rancho Santa Fe

ANSWER: This is an example of a true sound bite that is inherently misleading. We tend to interpret “this century” as “in the past 100 years.” Such a record would indeed be surprising, even in the context of the natural variability resulting from the El Niño-La Niña cycle. Instead, “this century” means “in the 21st century.”

Global average temperatures in 2008 were the coolest since 2000. However, according to NASA's Goddard Institute for Space Studies, 2008 still ranks as one of the ten warmest years since instrumental measurement records began in 1880. All ten of the record warm years have occurred since 1997.

Why do (almost) all the planets orbit the sun on the same plane? I've seen numerous examples showing the trampoline and the bowling ball, but the reference suggests a two-dimensional plane. If the “bowling ball” were to weigh down spacetime, wouldn't it affect the entire area around the object and result in planetary orbits on numerous planes?

– Jeremy Quinn,
El Cajon

The textbook example of the bowling ball distorting a two-dimensional rubber sheet is not intended to show why the planets orbit the sun on the same plane. It is an analogy for Einstein's explanation of gravity.

Matter distorts the fabric of four-dimensional spacetime similar to the way a heavy ball distorts a two-dimensional rubber sheet. The analogy is simplistic, and the planets could indeed orbit the sun on different planes.

The reason they are nearly all in the same plane has to do with how the sun and planets formed from an interstellar cloud of gas, the solar nebula. A cataclysmic event, such as a shock wave from an exploding star, was the likely initial trigger for the collapse of the solar nebula. As the cloud of gas shrank in radius, it began to spin faster and faster, like a skater pulling in her arms.

During collapse, clumps of gas within the cloud collided and merged, with the new clumps having the average velocity of the original clumps. Therefore, motions became more orderly, and the cloud flattened into a disk. Because the solar system formed from this disk, the planets' orbits remained within the disk's plane.



