Sun’s gamma ray bursts, supernovas pose threat to Earth

Nov. 6, 2013

By Paul Bressler

Prof. Robert Benjamin spoke of the sun as the primary hazard to Earth at Upham Hall Friday night and what it means for the future.

Benjamin, physics department chairperson and associate professor of physics, assured the audience at the end, that although we are not in any immediate danger, there is always the possibility.

“The principal danger to us is our sun,” Benjamin said.

The reason the sun is the biggest threat to us is due to the fact that we are much closer to the Sun than any other star in our universe.

Eventually, the Earth will be cooked by the Sun, but that will not happen for another 3.5 billion years from now. At which point, the Sun’s luminosity will increase by 40 percent and in effect will boil all of our oceans away. This process will no longer allow our planet to be livable.

We do not need to fear the sun because of all the protection we have from it. The gamma-rays and X-rays emitted from the sun are absorbed by our atmosphere. We also have a magnetic field that deflects the majority of particles that come from the sun.

The only possible exception to the sun being the principal hazard to the Earth is if gamma-ray bursts or double degenerates were to occur. Even with today’s modern astronomical technology, we would not be able to see this coming.

“They’re completely invisible until they explode in a mind-reining explosion,” Benjamin said. “And so, if we happen to have a double degenerate system within say 40 light years of the sun, we’re toast.”

Many people are not worried about the sun, and think that supernovae pose a threat to not only our well-being, but also the Earth’s. One of Benjamin’s key points to take away from the lecture was in order for a supernova to severely disrupt our atmosphere it would need to explode within about 20 light years of Earth.

Supernovae are created by either the collapse of a massive star or the introduction of nuclear fusion in a degenerate star. Supernovae will ultimately lead to a stellar explosion. Once activated, the explosion releases a burst of radiation into our galaxy.

A supernova can realistically radiate as much energy as the sun is expected to emit over its entire life span. Supernovae do not pose the immediate threat to us that the sun will due to the distance.

Astronomers have the ability to detect nearby Type II supernovae and their implications for our future. These types of supernovae are detectable, because they come from luminous stars.

It is also believed with almost certainty that astronomers could detect any future nearby Type Ia supernovae. These types do not have the luminosity of a Type II, but they have episodes of X-ray flashes that would be detectable.

Benjamin’s lecture was titled “Will Life on Earth Survive Deneb’s Supernova?” The observatory portion of the lecture was cancelled due to the weather.

Dr. Paul Rybski, associate professor of physics and director of the Whitewater Observatory, encouraged those in attendance to continue to attend the upcoming lectures.

“I hope to see all of you next week,” Rybski said.

Prof. Juliana Constantinescu, physics lecturer, is scheduled to present “Reversal of Earth’s Magnetic Field – what really will happen?” on Nov. 8.

Rybski will wrap up the series of popular lectures on Nov. 15 with, “What Do We Know About the Russian Meteor Event?”

UW-Whitewater students, faculty members and the general public are invited to attend. There is no fee for any of the lectures, and reservations are not necessary.

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