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Swift Education and Public Outreach
Goddard Space Flight Center Sonoma State University Education and Public Outreach

Swift Outreach Helpdesk Questions and Answers

Sent: Thursday, November 2, 2006
Subject: Can a Gamma-ray destroy the earth There is so much talk about a huge gamma-ray destroying the earth. Is that possible?

Answer provided by Phil Plait (SSU NASA Education Resource Director):
I think what you mean is a "gamma-ray burst", and not just a gamma ray. Gamma rays are a form of light, like the light we see, except with millions or even billions of times the energy. It takes a very powerful event to create gamma rays.

A gamma-ray burst (or GRB) is just such an event! It's a huge explosion in space, and scientists think they occur when either a very massive star explodes, or two ultra-dense neutron stars collide. Either way, we think a GRB signals the birth of a black hole.

Every GRB ever seen (and we've seen almost 3000 of them) has been very, very far away-- hundreds of millions to billions of light years distant. At those extreme distances, they can't hurt us.

But if one were close, then yes, it could damage the Earth, or even destroy it totally! But it would have to be very close, probably inside our own Milky Way Galaxy. In any one galaxy, GRBs are extremely rare, and we don't know of any stars that might form one anytime soon (like, in the next several million years). So we're probably safe.

Some scientists think that in the distant past, a nearby GRB did cause a mass extinction on Earth-- the Ordovician event, which was 440 million years ago. About 70% of all species on Earth were wiped out, and no one is really sure what caused it. A GRB is a possibility, but it has not been conclusively proved. You can read more about that on this Kansas University website

So the answer to your question is technically "yes", but I wouldn't let it cause you to lose any sleep!

You can read more about GRBs at the Swift website.

Sent: Saturday, May 14, 2005 10:04 PM
Subject: Quantum physics (and NASA stuff from so very long ago)
I have so many fond memories of NASA 4-color literature in the '60s: Mercury, Gemini, Apollo. Some of these things, which then were really dreams in the making, are now beyond anybody's wildest dreams. Swift, I think, touches on, or more accurately brings to life, some of these '60's dreams. What's the impact of Stephen Hawking on these and related fields of interest?

Answer provided by Lynn Cominsky (SSU E/PO Director):
Stephen Hawking was catapulted into physics superstardom when he predicted that black holes might actually decay with time. The effect is very complicated, involving the very different fields of General Relativity and Quantum Mechanics.

Einstein's Theory of General Relativity can be used to model the effects of the intense gravity near a black hole. Scientists had been using relativity to model black holes for decades before Hawking. Hawking, however, added quantum mechanics to the mix, and predicted that black holes can actually emit particles, which is the opposite of what people expected! After all, black holes are known for eating down matter, not emitting it. Still, the effect means that over time, black holes lose mass, and the rate they emit depends on the mass of the black hole. A "regular" black hole, like the kind made when a massive star explodes, might live for 10^67 years or more, far longer than the age of the Universe (which is about 10^10 years). But a tiny black hole, one with the mass of, say, a mountain, would decay in only a few billion years. If such a tiny black hole, sometimes called a "quantum black hole", were created in the Big Bang, then it would be in its final stages of decay right now. In the last millisecond, it would emit a huge flash of high energy particles and light.

These are different than the gamma-ray bursts Swift detects, in that normal GRBs happen when black holes are born, not when they die. Is it possible to detect such a flash from a dying black hole? I don't think anyone knows for sure, and no one even knows if quantum black holes exist! But if one is detected, it will confirm Dr. Hawking's conjectures and place him firmly in the same pantheon as Newton and Einstein.

Sent: Wednesday, May 04, 2005 12:01 PM
Subject: EM Spectrum
Can you explain to me the connect between an electromagnet (a common activity when studying electricity is to create one) and the electromagnetic spectrum?

Answer provided by Phil Plait (E/PO Education Resource Director) and Lynn Cominsky (SSU E/PO Director):
Magnetism and electricity are related-- they're like two sides of the same coin! One way a magnetic field can be made is by a *changing* electric field, and vice-versa. Both magnetism and electricity can be generated by moving electrons.

Imagine a single electron moving at a constant speed in a straight line. It makes an electric field, but that field is constant-- it doesn't change. So no magnetic field is made.

But now imagine an oscillating electron--one moving back and forth. The electric current makes an electric field, as before, but this time that field is changing, because the speed of the electron is changing. This makes a magnetic field. But that magnetic field also changes with time, because the *current* is changing as the speed of the electron changes. That change in the magnetic field sets up a changing electric field. And since there is an oscillation going on, you can think of the magnetic and electric fields making each other! The changing current makes the magnetic field, which changes, creating an electric field, which changes, creating a magnetic field, and 'round and 'round we go.

They self-sustain, and what you get is an electromagnetic wave. The words "electromagnet" and "electromagnetic wave" refer to the fact that in both cases electricity and magnetism are working together to cause the phenomena.
According to the laws of physics, such a wave must travel at the speed of light, and in fact this wave *is* light. That's why we call light an electromagnetic wave.

A good place to read about this is Nick Strobel's Astronomy Notes web site: (he also has some nice graphics to go along with his explanation), and he continues the discussion here:

Sent: April 10, 2005 12:07:37 AM EDT
Subject: GRB Theories
Is there any reason why the explanations can not include all three?
Gamma-ray bursts (GRBs) are the most powerful explosions the Universe has seen since the Big Bang. They occur approximately once per day and are brief, but intense, flashes of gamma radiation. They come from all different directions of the sky and last from a few milliseconds to a few hundred seconds. So far scientists do not know what causes them. Do they signal the birth of a black hole in a massive stellar explosion? Are they the product of the collision of two neutron stars? Or is it some other exotic phenomenon that causes these bursts?

Answer provided by Lynn Cominsky (SSU E/PO Director):
There is no reason why the explanation for GRBs could not include all three scenarios listed - in fact, there could be many more than three causes for GRBs. The reason that there are two popular scenarios is that observationally GRBs appear to be divided into two classes: those shorter than 2 seconds, and those longer than 2 seconds. If this classification scheme is correct, then it would follow that there are two different causes for the bursts. However, there are other properties of the bursts which differ and could lead to alternative explanations. The jury is still out as to the classification scheme and the associated mechanisms, especially for the shorter class of bursts.

Sent: Monday March 21, 2005 1:14 PM
Subject: Swift images
How was the Swift Observatory put into orbit and what was the cost of this mission?

Answer provided by Lynn Cominsky (SSU E/PO Director):
Swift was launched into orbit using a Delta 2 rocket that had 2 stages and 3 rocket boosters. The total cost was about $250 million, including international participation from the UK and Italy.

Sent: Saturday, March 19, 2005 10:10 AM
Subject: Swift distance
What is the distance of the Swift satellite from the equator?

Answer provided by Phil Plait (E/PO Education Resource Director):
Swift was launched on an orbit that is tilted by 20 degrees to the Earth's equator. That means it can swing 20 degrees north or south of the Equator, which translates to about 1300 miles north or south of the Equator. This is a rather low inclination orbit for a satellite launched from Florida, which means that Swift never gets high enough above the horizon to see for most people in the United States.

Sent: Friday, March 11, 2005 4:14 AM
Subject: Swift images
Will we be able to 'see' images of grbs on the swift site of the items of note that the swift is detecting? in particular, will we get images of the same point in the sky that the swift detects in visible/uv, and x-ray, and gamma ray so that we can 'see' what the swift is able to see?

Answer provided by Sarah Silva (E/PO Program Manager):
Yes, you will be able to see Swift images from the site. Right now the best place to find these images is in the tab called "Swift Results" and "quick look data" (these are both links off of the main swift pages.) We also have the page which is great for everyone. This site too will also have the images taken by swift of the various bursts. Of course, we are still in the check out phase for Swift so everything is not yet up and running. We also don't have many images taken yet.

Sent: Wednesday, March 02, 2005 7:51 AM
Subject: GRB origins
In regards to the origin of Gamma Ray Bursts: All of the press release information regarding the Swift mission science to date seems to infer that the current assumption/hypothesis that GRBs are related to the origins of 'new' black holes throughout the distant cosmos. While satisfying my own curiosity on the matter, I've recently stumbled upon an argument that associates GRBs and the deaths of relatively small, primordial black holes. Is it known whether any of the researchers on the Swift network working along such lines?

Answer provided by Lynn Cominsky (SSU E/PO Director):
The idea that GRBs could be associated with the death of relatively small, primordial black holes derives from calculations done by Stephen Hawking.
So-called "Hawking radiation" is emitted from black holes as they evaporate, and smaller ones evaporate more quickly, perhaps quickly enough to emit radiation in the form of a burst. However, this is very faint radiation, and to see bursts of this type, they must originate very close to Earth. Since the "long" GRBs, i.e. those with durations more than two seconds, have been shown to occur at distances of several to more than 10 billion light years, the primordial burst explanation does not work.
There is still a chance that it could apply to "short" GRBs, those with durations less than two seconds, as the distances to these bursts are still unknown.

Sent: Saturday, February 19, 2005 2:33 PM
Subject: SGR 1806-20 Blast
I noticed that seconds after the initial blast of light, a doppler-like wave emanated from that point and seemed to fly past the SWIFT camera. This "wave" appeared to be traveling at close to light speed, what was it's composition?
Referring Page:

Answer provided by Lynn Cominsky (SSU E/PO Director):
The wave in question represented the light coming from the SGR in the initial blast. The animation showed it as coming out afterwards, this was incorrect.

Sent: Saturday, February 05, 2005 2:51 PM
Subject: GRB afterglow in the radio wave spectrum
1. Has anyone ever tried to follow up Gamma Ray Burst events in the Radio wave portion of the spectrum in real time?

Answer provided by Dale Frail (NRAO):
Many radio observations have been done of the afterglows of GRBs. The radio emission comes from the same shock that gives rise to the optical and X-ray emission but the radio reaches peak brightness 5-10 days after the burst.
This "afterglow" emission is associated with the synchrotron emission from shocked electrons in the jet. (Synchrotron emission is light emitted due to the acceleration of the electrons by strong magnetic fields.) At early times, the shocked fireball is too small to produce significant radio emission. It is only when the shock expands that the radio gets bright enough to detect.

Sent: Saturday, February 05, 2005 2:51 PM
Subject: GRB afterglow in the radio wave spectrum
2. Are there any radio telescopes available in the world with the capability of quickly focusing on such an event? (e.g. electronic positioning based on phased array RADAR technology)

Answer provided by Dale Frail (NRAO):
Yes, despite the fact that we expect the emission to be weak, there have been several experiments to detect "prompt" radio emission. None of these have been successful but we keep trying. The most sensitive telescopes in the world first start detecting the radio afterglows about 24 hrs after a gamma-ray burst.

Sent: Saturday, February 05, 2005 2:51 PM
Subject: GRB afterglow in the radio wave spectrum
3. What information could potentially be gleaned by radio wave measurements of a real time Gamma Ray burst?

Answer provided by Dale Frail (NRAO):
If you could detect prompt radio emission from a gamma-ray burst there are several things you could do. The most important would be to measure the delay in the arrival of the radio signal. A delay is expected because the signal gets to us only after propagating through a large amount of ionized gas between us and the source. Detecting prompt radio emission would be a unique probe of the gas density of the early Universe.

Sent: Thursday, January 21, 2005
Subject: Dimensions of the Swift Satellite
I am conducting a presentation for my high school and I had a few quick questions. Who is responsible for or had the idea for the swift telescope?
Where is it now? What's its purpose to scientists what are they trying to find out with it? and how is it going to get to were it is going or how did
it get to were it was going?

It was proposed by Neil Gehrels and a team from Goddard Space Flight Center.
Work began in 1997 to formulate the mission in response to an upcoming opportunity for MIDEX satellites - Medium-sized Explorers, which was announced in 1998. In 1999, Swift was chosen for a Phase A study, as one of
5 missions for possible flight opportunities. Later that same year, Swift was one of 2 selected for flight. It was launched into orbit on 11/20/04. It is in a circular orbit, about 600 km above the Earth, and about 20 degrees inclination to the Earth's equator. It was launched using a Delta rocket, from Cape Canaveral Air Force Station, in Florida. Its purpose is to study gamma-ray bursts, the most powerful explosions seen in the Universe today. A few times per day, somewhere in the Universe, a gamma-ray burst occurs.
These bursts are believed to signal the birth of black holes. Swift's mission is to study these bursts, and try to understand the nature of these mysterious explosions.

-Written by Lynn Cominsky Swift E/PO Lead

Sent: Friday, December 10, 2004
Subject: Dimensions of the Swift Satellite

Could you please let me know the diameter of the swift satellite and the length? This is for a measuring activity for students.

Swift is 18.5 feet tall x 17.75 ft wide.

Sent: Wednesday, December 01, 2004
Subject: Gamma-Ray Burst

Just wondering if I possibly witnessed two gamma-ray bursts tonight around 7:10 PM. I live in Fayetteville, NC (northeastern section of Cumberland County). There was a brilliant light in the Northern section of sky which I caught with the corner of my eye, and then (a second later) another brilliant flash of light a little lower than before but at a declining angle. After second flash, nothing more occurred. No trail like a falling star or comet would make.

A common event often mistaken by people in the sky to be a Gamma-Ray burst is an Iridium Flare. If you visit this link, then put in your latitude and longitude, you will be able to see if there were any of these flares reported during this time.

If you have a question about Swift, please contact us via the Feedback form.

This page was last modified on Friday, 02-Jan-2009 12:34:24 PST.

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