Expert: Jesse Martinez - 12/2/2009

Question
QUESTION: Please answer according to scale of 5 (as detailed as possible).

Regarding Solar Cycle 24, we've not had any sunspots lately.  Could this pent up energy of the sun would result in massive Solar Flares?  Is there any remote possibility of temporarily halting the earth's rotation on its axis?  What would happen to Earth if it were to stop rotating, say for about 36 hours?  My own observations if this were to happen, while the Earth maintains its current orbit, it's likely the Sun would rise from the West!  Could you please comment...Thanks in advance.

ANSWER: Hi. I'd be glad to answer and comment on the question, or should I say three questions. I will answer them in order.

Most experts believe that the upcoming cycle maximum will be of below average intensity. This will likely decrease the chances of massive solar flares. The maximum will be in May 2013. The maximum sunspot number is expected to be 90. http://spaceweather.com/glossary/sunspotnumber.html

The actual number visible will depend on your observation variables. But you will notice from the graph  in the link above that 90 is a very low maximum throughout the years. The years of 1989 and 1991 were fantastic, the best I've ever seen. About half of the top twenty solar flares ever recorded in recent years occurred in those years. This next one is poised to disappoint as a maximum and for large flares, since the two are related.

The next question is one I have been hearing lately. "What happens when the earth stops rotating for 36 hours?" I think I know why now. I believe it has something to do with the Mayan predictions about the end of the world in 2012 and possible references in recent sci-fi movies. Lets first examine the physics of such an event. There is a tremendous amount of energy in the form of angular momentum in the earth's rotation. No amount of gravitational force or any other I could imagine can stop the rotation within a short period of time. Even if it could the earth would be utterly destroyed. If you suddenly within a few seconds slowed down the earth's rotation by even a small amount like one second a day to 23 hours, 59 minutes and 59 seconds, the results would be catastrophic. Earthquakes, tidal waves and volcanic eruptions would be triggered. I haven't done the math, but I bet it would actually lead to the end of a lot of life. In order to stop the earth suddenly without causing it to tear apart in pieces would be to transfer its angular momentum to another body. Then after 36 hours, the momentum could be transferred back and the earth could resume rotating as usual. How can this happen? I don't know.

However, lets say it could happen. The earth stops rotating and faces a fixed point in the sky. If you were in a place on the equator where the sun was halfway set on the horizon in the evening, it would appear to slow down dramatically. The sun's motion in the sky would slow down to one degree of arc per day. The remaining 1/4 degree that was still above the horizon would continue setting but would take six hours to finish. This leads to the answer to question three.

No, the sun wouldn't rise in the west anywhere. The sun would continue its east to west motion but at the rate of one day a year. Going back to the changes that would happen it the 36 hour stoppage could happen without us being torn apart. There would be no long term changes. The people that get stuck with the sun high in the sky in summer at the equator would probably have the worst of it, especially in places where no cooling is available. It is conceivable that the temperature could rise above the boiling point of water during a prolonged exposure to midday sun!

There you are. If I missed something or you need to ask a followup, please do. I always enjoy exercising my mind, so thank you.

Don't stop thinking and dreaming,
Jesse



---------- FOLLOW-UP ----------

QUESTION: Thank you for the prompt answer...

Could we reexamine the hypothetical celestial mechanics scenario/simulation of the earth ceasing to rotate on its axis while maintaining its current orbit around the sun (also anti-clockwise)....?

There is a graphical representation on this website:
http://fouadfroth.wordpress.com/2009/10/28/astrophysics-in-the-quran/

Does the possibility of the Sun rising from the West seem plausible in this scenario...

My own understanding, it is the rotation of the Earth counter clockwise is what is giving us Sun rise from the East.

Cheers...

Answer
Thanks for sending that link. I got mixed up on the CCW revolution of the earth around the sun. Now that I have my bearings. I see that a stoppage of the earth's rotation would indeed cause a slow motion sunrise from the west in the scenario I described in my answer. Yes a few people would see a western sunrise should this extremely unlikely situation "arise".