Day 68: Pluto re-demoted, sunspots hit a new low

Pluto (left) and its moon Charon, from www.solarsysteminfo.ca

I saw a few great April Fool’s jokes today, but this one at NASA Watch really got the prize:

“Pluto is Now Just a Fairly Large Rock”

With perfect mock-serious delivery, blog author Keith Cowing reported it like straight news — given the growing number of solar system bodies in Pluto’s neighborhood, the beleaguered little former planet really isn’t even deserving of “dwarf planet” status any more.

He even made up an official-sounding quote from the International Astronomical Union, astronomy’s official naming body: “Based on new observational evidence of more objects of significant size in the outer solar system, Pluto will no longer be described as a dwarf planet,” said David Perel, chair of the IAU’s Committee on Designations. “We will be meeting to consider a permanent name for the category of objects that Pluto falls under. In the meantime, we are describing it with the working label of ‘FLR’ (Fairly Large Rock).”

He almost had me going for a while there! But I knew it was a fake when he announced NASA’s plans to re-route the New Horizons mission, which has already reached Saturn on its way to Pluto:  “Considering the relative scientific merits and the value to the public, New Horizons will now be reprogrammed to orbit Mars,” said Nick Denton, acting deputy assistant associate administrator for NASA’s Science Mission Directorate.

Cowing’s excellent blog (even when he’s being serious) is here. Other great April Fool’s stories included Nancy’s Atkinson’s leg-puller at Universe Today, Galaxy Zoo Team Discovers New Class of Galaxy Cluster, and the annual holiday spoof at the (Flagstaff) Arizona Daily Sun newspaper, City treasures auctioned. Talk about laughing in the face of adversity! Finally, National Geographic News put together a fun and enlightening photo gallery of four historic science hoaxes.

And now, for something real. NASA announced today that the Sun is at an unexpected new low in its cycle of activity, as measured by sunspots. It’s normal for the Sun to go through sunspot cycles, usually on an 11-year scale. We’ve hit the bottom right on time. But NASA scientists are surprised at how quiet the Sun has been over the past year or so — quieter than at any time in the past century, one expert says.

The sunspot cycle from 1995 to the present. The jagged curve traces actual sunspot counts. Smooth curves are fits to the data and one forecaster's predictions of future activity. Credit: David Hathaway, NASA/MSFC.

NASA’s story is here.  What’s striking to me is how little solar physicists actually know about the Sun. No one understands what causes the sunspot cycles. Only within the past couple of weeks has a plausible explanation arisen to explain why the Sun’s corona is so much hotter than its surface. And we have no idea what will happen with the Sun going forward — whether we’ll stay in a prolonged minimum, or rebound, as expected, into a new period of activity.

The evidence is spotty, but a prolonged solar minimum might have contributed to a very cold, icy spell in Earth’s history called the Little Ice Age, which started around the 14th Century and lasted a few hundred years. Scientists believe the coldest part, toward the end of the spell, coincided with a period of low sunspot activity documented by Galileo with the world’s first telescopes.

Most solar researchers believe the Sun influences the Earth’s climate by about 25 percent. So, naturally, I think of global warming. Has the solar minimum been masking carbon-driven warming in the past few years? Will warming rear its head with a vengeance when the Sun’s activity returns? Or are we headed for a prolonged period of low sunspot activity, and a colder age — in which case reducing carbon emissions, as some “global warming deniers” allege, will be like casting off our blanket just before an ice storm? 

These are fascinating questions, and I feel lucky that I’ll probably see them answered in my lifetime.