Here are some pictures of today's (June 15, 2011) total lunar eclipse which was visible to observers in Europe, Africa, southern Asia, and Australia. This is one of the darkest and longest eclipses of this century lasting around 100 minutes and second only to the total lunar eclipse on July 16, 2000.
These pictures were taken from Toledo, Spain between 11 pm and 12 am by my husband, who is attending a conference there! Below is the link to the photos (lots of Moon photos though -- taken with Nikon D3100 300mm lens in manual mode). If possible, enlarge (zoom in) and view the photos...you can see the craters as well..its awesome! Just a caution that the time set in Camera was for Saskatoon timing, so the photos carry a different time.
https://picasaweb.google.com/sanjeev.research/Moon?authkey=Gv1sRgCJOMqcSguqPDwgE#
Wednesday, June 15, 2011
New Maunder Minimum?
At the annual meeting of the Solar Physics division of the American Astronomical Society, Frank Hill, Matt Penn, William Livingston, Richard Altrock and collaborators presented data indicating that the Sun may be heading that direction after Solar Cycle 24 is complete. So what does this mean?
Well first lets go over what the Maunder Minimum was. Humans have been observing sunspots regularly since Galileo first turned his telescope towards the Sun. (WARNING: DO NOT DO THIS UNLESS YOU HAVE A SOLAR FILTER FOR YOUR TELESCOPE!!!) Since that time a record has been kept of the number of sunspots on the Sun. This one of the longest scientific observing records to date, with over 400 years of data. It was discovered that the number of sunspots rises and falls over a period of 11 years. However, something strange happened to this pattern between 1645 and 1715, known as the Maunder Minimum. During this time the Sun showed few if any sunspots.
Since that time heliophysicists have discovered the cause of sunspots and the sunspot cycle. Sunspots are caused by regions of intense magnetic field on the Sun. This magnetic field keeps the region of the sunspot cooler than the surrounding plasma, thus the sunspot looks dark. The cycle of the sunspots is related to the cycle over which the magnetic field on the Sun reconfigures. Every 11 years, the magnetic field of the Sun flips its direction so that the North pole becomes the South and visa versa. During a minimum in Solar activity the magnetic field is stable in its orientation. However, as solar activity increases, indicated via the proxy of an increasing sunspot number, the magnetic field becomes chaotic as it flips direction. This chaotic field is the seed for the solar activity. Thus the Sun flips its magnetic field every 11 years, leading to the 11 year sunspot cycle.
Helioseismologists have recently uncovered more detail about this process. It all relates to the different flows with in the Sun's convection zone. In this region, particularly the region known as the tachocline, the magnetic field for the Sun is thought to be generated. Scientists have discovered large scale flows which control the motion of sunspots on the Sun. They have also discovered jet streams, similar to the ones found on Earth, which can be used to predict when new sunspot cycles begin. This was used to predict the late onset of the current sunspot cycle labelled Cycle 24.
Current data from Frank Hill's group shows that the jet streams for Cycle 25, the next cycle, have not formed yet which is unusual. If they don't form at all Cycle 25 probably won't happen. Penn and Livingston presented data that indicated that the sunspots have been weakening over the past 2 cycles. Altrock presented data showing that the field accumulation at the poles of the Sun has slowed as well. The combined data indicates that Cycle 25 will either be weak or not occur at all. If Cycle 25 doesn't happen it may be the start of another Maunder Minimum (aka grand minimum).
So what would be the implications for us here on Earth if another Maunder Minimum were to occur? Well there would be less activity from the Sun. A lower number of solar flares and Coronal Mass Ejections. This would lead to lower auroral activity. It would also make it safer for people out in space as the chances of being exposed to harmful radiation from the Sun would decrease. It would also lower the danger activity from the Sun poses to electronics in space and on Earth. The Sun would also put out less radiation making it slightly cooler here on Earth. In fact the Maunder Minimum coincided with the middle Little Ice Age in the 17th century. While the minimum certainly contributed to the Little Ice Age, the main cause was vulcanism here on Earth, so don't expect the cooler Sun from a minimum to counter act global warming. In fact the Sun would have to get 10 times cooler than it would become during a grand minimum to make up for the net effect of greenhouse emissions, so no worries of a new Ice Age yet.
A grand minimum would also be extremely interesting to heliophysicists. This is because we don't know what caused the original Maunder Minimum. Also while we have a pretty good idea about how the magnetic field on the Sun works, we still know very little about its generation. Observing another grand minimum would help us to understand both of these topics.
So will the Sun go into another grand minimum or not? Only time will tell if the predictions from the recent data hold true. As more data is accumulated better models will be generated and we will get a better idea of how Cycle 25 will likely play out. Ultimately, as with weather forecasting, you will never know for sure until you get to the actual date of the event to see if it happens.
Well first lets go over what the Maunder Minimum was. Humans have been observing sunspots regularly since Galileo first turned his telescope towards the Sun. (WARNING: DO NOT DO THIS UNLESS YOU HAVE A SOLAR FILTER FOR YOUR TELESCOPE!!!) Since that time a record has been kept of the number of sunspots on the Sun. This one of the longest scientific observing records to date, with over 400 years of data. It was discovered that the number of sunspots rises and falls over a period of 11 years. However, something strange happened to this pattern between 1645 and 1715, known as the Maunder Minimum. During this time the Sun showed few if any sunspots.
Since that time heliophysicists have discovered the cause of sunspots and the sunspot cycle. Sunspots are caused by regions of intense magnetic field on the Sun. This magnetic field keeps the region of the sunspot cooler than the surrounding plasma, thus the sunspot looks dark. The cycle of the sunspots is related to the cycle over which the magnetic field on the Sun reconfigures. Every 11 years, the magnetic field of the Sun flips its direction so that the North pole becomes the South and visa versa. During a minimum in Solar activity the magnetic field is stable in its orientation. However, as solar activity increases, indicated via the proxy of an increasing sunspot number, the magnetic field becomes chaotic as it flips direction. This chaotic field is the seed for the solar activity. Thus the Sun flips its magnetic field every 11 years, leading to the 11 year sunspot cycle.
Helioseismologists have recently uncovered more detail about this process. It all relates to the different flows with in the Sun's convection zone. In this region, particularly the region known as the tachocline, the magnetic field for the Sun is thought to be generated. Scientists have discovered large scale flows which control the motion of sunspots on the Sun. They have also discovered jet streams, similar to the ones found on Earth, which can be used to predict when new sunspot cycles begin. This was used to predict the late onset of the current sunspot cycle labelled Cycle 24.
Current data from Frank Hill's group shows that the jet streams for Cycle 25, the next cycle, have not formed yet which is unusual. If they don't form at all Cycle 25 probably won't happen. Penn and Livingston presented data that indicated that the sunspots have been weakening over the past 2 cycles. Altrock presented data showing that the field accumulation at the poles of the Sun has slowed as well. The combined data indicates that Cycle 25 will either be weak or not occur at all. If Cycle 25 doesn't happen it may be the start of another Maunder Minimum (aka grand minimum).
So what would be the implications for us here on Earth if another Maunder Minimum were to occur? Well there would be less activity from the Sun. A lower number of solar flares and Coronal Mass Ejections. This would lead to lower auroral activity. It would also make it safer for people out in space as the chances of being exposed to harmful radiation from the Sun would decrease. It would also lower the danger activity from the Sun poses to electronics in space and on Earth. The Sun would also put out less radiation making it slightly cooler here on Earth. In fact the Maunder Minimum coincided with the middle Little Ice Age in the 17th century. While the minimum certainly contributed to the Little Ice Age, the main cause was vulcanism here on Earth, so don't expect the cooler Sun from a minimum to counter act global warming. In fact the Sun would have to get 10 times cooler than it would become during a grand minimum to make up for the net effect of greenhouse emissions, so no worries of a new Ice Age yet.
A grand minimum would also be extremely interesting to heliophysicists. This is because we don't know what caused the original Maunder Minimum. Also while we have a pretty good idea about how the magnetic field on the Sun works, we still know very little about its generation. Observing another grand minimum would help us to understand both of these topics.
So will the Sun go into another grand minimum or not? Only time will tell if the predictions from the recent data hold true. As more data is accumulated better models will be generated and we will get a better idea of how Cycle 25 will likely play out. Ultimately, as with weather forecasting, you will never know for sure until you get to the actual date of the event to see if it happens.
Friday, June 10, 2011
Cool Solar Flare
This has been making the rounds and its pretty cool so I figure I would mention it as well. On June 7th the Sun let off a rather impressive solar flare which was observed by the satellites which observe the Sun, the Solar Dynamics Observatory (SDO), Solar and Heliospheric Observatory (SOHO), and Solar Terrestrial Relations Observatory (STEREO) to name a few. While this explosion wasn't out of the ordinary in terms of size or power, it was interesting because a lot of the material that was originally ejected fell back onto the surface of the Sun. This made for a rather spectacular movie by the SDO of material being shot up by the flare and then falling back to burn up on the surface.
So what is going on in the movie? Well a solar flare occurs because of magnetic fields on the Sun. Normally the magnetic fields on the Sun allow for material to flow off the Sun and form the Solar Wind. However if the fields get tangled that can stop that material from leaving the Sun and pressure begins to build up. Think of the Sun as a pot of boiling water and the Solar Wind as the steam rising off of the water to release energy. Tangled magnetic fields act like a very tight lid, which turns the Sun into a pressure cooker. The pressure builds and builds and builds until something gives way. In the case of the Sun, the magnetic field lines end up breaking in an event called reconnection. The reconnection event triggers the release of energy and material. This release is seen as a solar flare
In the case of this particular case the flare material didn't have enough energy to escape the Sun's gravity so it fell back on to the Sun. The material looks dark because it is cooler than the surface of the Sun. You will also notices that the material doesn't fall the way one expects. Rather it falls more slowly and is twisted around as it goes. This is the magnetic fields of the Sun at work again. The fields a strong enough to counter the force of gravity and channel the flow of material on the Sun.
The material from the flare that escaped was directed towards the Earth but only delivered a glancing blow to the Earth's magnetosphere. This caused a boost in auroral displays. We will be seeing more of these types of events from the Sun in the years to come as solar activity increases to its projected peak in 2013.
So what is going on in the movie? Well a solar flare occurs because of magnetic fields on the Sun. Normally the magnetic fields on the Sun allow for material to flow off the Sun and form the Solar Wind. However if the fields get tangled that can stop that material from leaving the Sun and pressure begins to build up. Think of the Sun as a pot of boiling water and the Solar Wind as the steam rising off of the water to release energy. Tangled magnetic fields act like a very tight lid, which turns the Sun into a pressure cooker. The pressure builds and builds and builds until something gives way. In the case of the Sun, the magnetic field lines end up breaking in an event called reconnection. The reconnection event triggers the release of energy and material. This release is seen as a solar flare
In the case of this particular case the flare material didn't have enough energy to escape the Sun's gravity so it fell back on to the Sun. The material looks dark because it is cooler than the surface of the Sun. You will also notices that the material doesn't fall the way one expects. Rather it falls more slowly and is twisted around as it goes. This is the magnetic fields of the Sun at work again. The fields a strong enough to counter the force of gravity and channel the flow of material on the Sun.
The material from the flare that escaped was directed towards the Earth but only delivered a glancing blow to the Earth's magnetosphere. This caused a boost in auroral displays. We will be seeing more of these types of events from the Sun in the years to come as solar activity increases to its projected peak in 2013.
Friday, June 3, 2011
Supernova in M51
A new Type II Supernova was detected on June 2nd in M51 by French amateur's (Stephane Lamotte and Marc Deldem). It has been confirmed by the Palomar Transient Factory, also the possible progenitor has been found. This makes it the second supernova detected in M51 in 6 years.
Type II Supernovae occur when a massive star ends it's life. When the core runs out of fusionable material the reduction in energy production removes pressure support from the interior of the star. The interior then collapses either into a neutron star or a black hole. In response to the collapse the rest of the star is ejected in a massive explosion of energy called a supernova.
Supernovae are detected all the time from the broader universe. However, one so close to us (about 7 Mpc) is uncommon. This gives astronomers an excellent opportunity to study these massive explosions in more detail than is available for a more distant supernovae. Even better would be a supernovae in our own Galaxy which is due to occur, (about 1-3 supernovae happen in our Galaxy every 100 years). The most recent Galactic supernovae was G1.9+0.3 whose light reached us 140 years ago.
Given the early nature of these observations, more details on this event will be forth coming as more instruments are brought to bear to observe the event.
Type II Supernovae occur when a massive star ends it's life. When the core runs out of fusionable material the reduction in energy production removes pressure support from the interior of the star. The interior then collapses either into a neutron star or a black hole. In response to the collapse the rest of the star is ejected in a massive explosion of energy called a supernova.
Supernovae are detected all the time from the broader universe. However, one so close to us (about 7 Mpc) is uncommon. This gives astronomers an excellent opportunity to study these massive explosions in more detail than is available for a more distant supernovae. Even better would be a supernovae in our own Galaxy which is due to occur, (about 1-3 supernovae happen in our Galaxy every 100 years). The most recent Galactic supernovae was G1.9+0.3 whose light reached us 140 years ago.
Given the early nature of these observations, more details on this event will be forth coming as more instruments are brought to bear to observe the event.
Wednesday, June 1, 2011
Time-lapse with a Rotating Earth
It used to be thought that the Earth was stationary and the sky rotated around the Earth. However, with the advent of the heliocentric model and many proofs of the Earth's rotation we now follow the Copernican view of the universe in science. In this view the Earth is no longer the center of the universe but rather just a normal component of it, occupying no special physical place. Thus physics that occurs here is the same as it occurring in any other location, and there is no proper center to the universe. Einstein's theory of relativity then can be just thought of as a natural extension of the Copernican principle.
All that aside, we here on Earth continue to perceive the sky rotating around us rather than the other way around. This is especially evident in time-lapse photography of the sky. Well today's APOD takes us into a different frame than we are used to for time-lapse movies. Instead of using the ground as stationary, the movie has been edited such that the sky is stationary and the Earth moves instead. One can see the ground tumble and move all over the place as it rotates relative to the broader universe. You can also see in this movie the telescope array for the Very Large Telescope in Chile as well as laser guide stars shooting up from the telescopes. Definitely gives one a different perspective on our place in the universe.
All that aside, we here on Earth continue to perceive the sky rotating around us rather than the other way around. This is especially evident in time-lapse photography of the sky. Well today's APOD takes us into a different frame than we are used to for time-lapse movies. Instead of using the ground as stationary, the movie has been edited such that the sky is stationary and the Earth moves instead. One can see the ground tumble and move all over the place as it rotates relative to the broader universe. You can also see in this movie the telescope array for the Very Large Telescope in Chile as well as laser guide stars shooting up from the telescopes. Definitely gives one a different perspective on our place in the universe.
Tuesday, May 24, 2011
The Crab's Gamma-Ray Flare
As noted on this blog last month, the Crab Nebula was seen by the Fermi telescope to flare in the gamma ray band. The flare itself is pictured to the right and was the subject of yesterday's APOD. The flare itself lasted for 3 days and saw a 30 fold increase in emission from the Crab.Immediately after this occurred astronomers from all over the world looked with different instruments to see if there was increased emission from the Crab Nebula in other bands. No increase was detected though.
This is not the first time the Crab has done this, but it is confusing to astronomers trying to explain the flare. Since the flare lasts for only 3 days we know that the region of emission can't be that large. Since it was seen only in the gamma-rays seen by Fermi, we know that it is probably due to fluctuations in the synchrotron spectrum of the nebula. At these high energies the synchrotron light that is being seen is coming from the highest energy electrons, so fluctuations at these energies indicates fluctuations either in the magnetic field or the population of the highest energy electrons. No one is quite sure which, and while several theories have been tossed about, there is no favored model.
The variability in the gamma-ray is also a little concerning for observers in those bands as the Crab Nebula is used as a standard calibration source since it's emission is thought to be relatively steady. This is still likely true in the normal state, so astronomers just have to be aware if they are observing during a flaring state or not. Also most of the experiments using the Crab as a standard work in the TeV gamma-ray which is much higher energy than Fermi and do not see any fluctuations in the Crab's emission.
Wednesday, May 18, 2011
GOES Captures Last Month's Tornado Activity in the US Southeast
Well not exactly. GOES (Geostationary Operational Environmental Satellite) captured the storm systems which generated the series of tornadoes which ravaged the deep south of the US. The movie, linked here, shows a time-lapse of the weather systems that occurred in April along with red points indicating where tornadoes were detected by ground stations and observers. One can see that some of the storm systems stall over the midwest generating a series of tornadoes there, where as other systems sweep across the country spawning tornadoes on their way.
So what is GOES anyways? GOES is a series of satellites run by NOAA's National Weather Service (National Oceanic and Atmospheric Administration). There are 3 active GOES satellites. Each of them sit in geosynchronous orbit. These type of orbits are special, originally proposed by Arthur C. Clarke, in that the amount of time it takes to complete the orbit is the same as the amount of time it takes the Earth to rotate. Thus a satellite in this orbit, at a radius of about 42,000 km, appear to hover over the same region on the Earth. This makes it an ideal location for communications and weather satellites. The 3 active satellites in GOES watch three different regions of the western hemisphere. The three active satellites are dubbed GOES-West, which watches the western US and Pacific Ocean, GOES-East which watches the eastern US and Atlantic and GOES-South which covers South America.
The GOES satellites have a variety of instruments to measure weather phenomenon on Earth. They have visible light camera's to measure the reflected sunlight from the Earth, infrared cameras to see the heat emitting from the Earth, and sounding sensors which provide information about the atmospheric temperature, moisture and ozone levels. In addition GOES monitors the magnetic field and energetic particle environment in its orbit as well as monitoring the Sun.
With it's ability to provide a global images of current weather, GOES is an indispensable part of weather forecasting in both the US and Canada. Given how important GOES is for this there are always backup GOES satellites in orbit to take over in case one fails. Thus far, since 1975 there has been 15 GOES launched into orbit. Currently GOES 11-13 are active with 1-10 having been decommissioned or turned to alternate uses (GOES 3 serves as a communications relay for the research station at the South Pole) . GOES 14 and 15 are the two backup satellites with newer models set to be launched in 2015. Thus GOES will be the premier general purpose weather satellites for years to come.
So what is GOES anyways? GOES is a series of satellites run by NOAA's National Weather Service (National Oceanic and Atmospheric Administration). There are 3 active GOES satellites. Each of them sit in geosynchronous orbit. These type of orbits are special, originally proposed by Arthur C. Clarke, in that the amount of time it takes to complete the orbit is the same as the amount of time it takes the Earth to rotate. Thus a satellite in this orbit, at a radius of about 42,000 km, appear to hover over the same region on the Earth. This makes it an ideal location for communications and weather satellites. The 3 active satellites in GOES watch three different regions of the western hemisphere. The three active satellites are dubbed GOES-West, which watches the western US and Pacific Ocean, GOES-East which watches the eastern US and Atlantic and GOES-South which covers South America.
The GOES satellites have a variety of instruments to measure weather phenomenon on Earth. They have visible light camera's to measure the reflected sunlight from the Earth, infrared cameras to see the heat emitting from the Earth, and sounding sensors which provide information about the atmospheric temperature, moisture and ozone levels. In addition GOES monitors the magnetic field and energetic particle environment in its orbit as well as monitoring the Sun.
With it's ability to provide a global images of current weather, GOES is an indispensable part of weather forecasting in both the US and Canada. Given how important GOES is for this there are always backup GOES satellites in orbit to take over in case one fails. Thus far, since 1975 there has been 15 GOES launched into orbit. Currently GOES 11-13 are active with 1-10 having been decommissioned or turned to alternate uses (GOES 3 serves as a communications relay for the research station at the South Pole) . GOES 14 and 15 are the two backup satellites with newer models set to be launched in 2015. Thus GOES will be the premier general purpose weather satellites for years to come.
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