Tag: sun

Solar Orbiter captures Mercury crossing in front of the Sun

9:36 am

Solar Orbiter spots Mercury in front of the Sun
Click for full movie.

The European probe Solar Orbiter successfully filmed Mercury as it crossed in front of the Sun — from the spacecraft’s perspective — on January 3, 2023.

The transit was captured by several different instruments on Solar Orbiter, as shown at the link. The picture above is a screen capture from the short movie made by its Extreme Ultraviolet Imager. The black disk is Mercury, moving from the left to the right. In the background the limb of the Sun can be seen, with a distinct feature flaring out from that limb.

For Solar Orbiter, this particular transit offered a valuable chance to calibrate the instruments. “It is a certified black object travelling through your field of view,” says Daniel Müller, Solar Orbiter Project Scientist at ESA. Thus, any brightness recorded by the instrument within Mercury’s disc must be caused by the way the instrument transmits its light, called the point spread function. The better this is known, the better it can be removed. So be studying this event, the quality of the Solar Orbiter data can be ever further improved.

If the transit also produced some spectacular images, so much the better.

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Sunspot update: The most sunspots since 2014

9:26 am

Time for my monthly sunspot update, based on NOAA’s monthly graph that tracks the number of sunspots on the Sun’s Earth-facing hemisphere. The newest graph, with December’s numbers added to the timeline, is below. As always, I have added some additional details to provide context.

In December the half-year pause in the ramp up to solar maximum ceased, with the Sun seeing the most sunspots since September 2014. This high activity far exceeded the predicted sunspot count for December 2023, almost doubling it. In fact, December’s sunspot count almost equaled the predicted peak for the upcoming solar maximum, which is not supposed to happen until sometime in 2025.

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Sunspot update: The Sun’s unprecedented pause to maximum continues

9:44 am

It is the beginning of the month, and NOAA has once again published its update of its monthly graph that tracks the number of sunspots on the Sun’s Earth-facing hemisphere. Below is the newest graph, adding November’s numbers to the timeline and annotated by me with some additional details added to provide context.

Sunspot activity dropped in November, though still remained significantly higher than the prediction, a sunspot number of 77.6 compared to the predicted number of 57.4. At 77.6, the Sun continues the pause that began in June in the ramp up to solar maximum. For the past half year the Sun’s sunspot output has essentially stalled at approximately the same level.

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China completes construction of world’s largest solar radio telescope array

9:36 am

China has now completed the construction of world’s largest solar radio telescope array, dubbed the Daocheng Solar Radio Telescope (DSRT), made up of 313 separate radio dishes laid out in a giant two-mile wide circle.

DSRT is focused on observing solar flares and coronal mass ejections (CMEs) which can interfere with or overload electronics and wreak havoc on and above Earth. CMEs are triggered by realignments in the star’s magnetic field that occur in sunspots, and when directed at Earth, can threaten power grids, telecommunications, orbiting satellites and even put the safety of astronauts aboard the International Space Station and China’s newly-completed Tiangong space station at risk.

Assuming China shares the data from this telescope with the rest of the world, it will function as a back-up to several very old NOAA satellites in orbit that NOAA has failed to replace. If China doesn’t share the data, however, the western world will become very vulnerable should its own satellites finally fail.

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Sunspot update: The pause in the ramp up to solar maximum continues

11:34 am

NOAA has once again published its monthly update of its monthly graph that tracks the number of sunspots on the Sun’s Earth-facing hemisphere. Below is that November graph, annotated by me with some additional details added to provide context.

Though sunspot number continued to be much higher than the prediction (almost double), October saw almost exactly the same number of sunspots as seen in September, which is why this new graph seems almost identical to last month’s.

In other words, the pause in the ramp up to solar maximum, first noted in August, continues.
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After 30 years the Geotail solar probe appears dead

8:01 pm

Launched in 1992 as a joint U.S./Japan project to study the tail of the Earth’s magnetosphere, the Geotail solar mission appears to be over, though engineers continue to work the problem.

Originally, Geotail was equipped with two data recorders to collect the mission’s scientific data. One data recorder failed in 2012 after 20 years of gathering information about the plasma environment around Earth. The remaining data recorder continued collecting data for 10 more years until it experienced an anomaly on June 28, 2022.

The team at JAXA discovered the error with the recorder and have been performing tests to investigate the cause and extent of the damage. Ongoing attempts to recover the recorder have been unsuccessful. Without a functioning recorder, the science data from the U.S. instruments can no longer be collected or downlinked. NASA, ISAS, and JAXA are deciding the best path forward for the mission given the failure.

When the solar wind hits the Earth’s magnetosphere, it pushes it away so that on the side away from the Sun a tail forms, almost like the wake of a ship.

Without any way to download the spacecraft’s data, however, Geotail’s value as a scientific probe is extremely limited. If engineers can still control it and adjust its orbit, however, then it might still be useful for a variety of engineering and orbital flight tests.

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Sunspot update: Activity again exceeds prediction but ramp up pauses

11:29 pm

NOAA this weekend published, as it does at the start of every month, its October update of its monthly graph that tracks the number of sunspots on the Sun’s Earth-facing hemisphere. As I have done since I started this website in 2011, I have published that graph below, with some additional details added to provide context.

An increase in sunspot activity in September wiped out the decline seen in August, so that the sunspot number in September once again matched or exceeded the numbers seen during the middle of the previous solar maximum from 2012 to 2014, a low period of activity between that maximum’s two peaks. Activity also continued to exceed the predictions of the panel of government solar scientists put together by NOAA.

At the same time, since May the ramp up to maximum has stalled, something I noted last month and has now become more evident.
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Sunspot update: Activity recovers mostly from last month’s decline

9:04 pm

It is the start of the month, and thus time to post NOAA’s monthly update of its graph tracking the number of sunspots on the Sun’s Earth-facing hemisphere. That graph is below, with some additional details added by me to provide a larger context.

After the first real decline in sunspot activity in June, the Sun recovered that decline almost completely in July. Though the ramp up to solar maximum has stalled somewhat in the last two months, the trend continues to point to a very active maximum, much higher than predicted as well as much stronger than the last very weak maximum in 2020.

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Sunspot update: For the first time in 2022, sunspot activity eases

3:58 pm

With the year half over, the Sun in June did something it had not done since the start of the year: The number of sunspots seen daily on the Sun’s visible hemisphere actually declined from the month before.

I know this because, as I do every month, I have posted below NOAA’s monthly update of its graph tracking the number of sunspots on the Sun’s Earth-facing hemisphere, with some addition details added to provide a larger context.

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Sunspot update: In May we had sunspots, sunspots, and more sunspots!

10:31 am

It is time for another sunspot update! On June 1 NOAA released its monthly update of its graph tracking the number of sunspots on the Sun’s Earth-facing hemisphere. As I do every month, I have posted it below, having added some addition details to provide a larger context.

In May the sunspot activity on the Sun almost literally exploded, producing some of the strongest solar flares in years as well as the most sunspots since the previous solar maximum in 2014. On several days there were as many as eight sunspot groups on the Sun, with one so large that it was visible to the naked eye on Earth (if viewed properly with a protective filter).
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ESA releases new images from Solar Orbiter

10:53 am

The Sun's south pole, as seen by Solar Orbiter at perihelion
The Sun’s south pole, as seen by Solar Orbiter at perihelion. Click for full movie.

The European Space Agency (ESA) yesterday released a few of the images taken by its Solar Orbiter spacecraft before and during its first perihelion (closest point in its orbit) on March 26, 2022.

The spacecraft was inside the orbit of Mercury, at about one-third the distance from the Sun to the Earth, and its heatshield was reaching around 500°C. But it dissipated that heat with its innovative technology to keep the spacecraft safe and functioning.

Solar Orbiter carries ten science instruments – nine are led by ESA Member States and one by NASA – all working together in close collaboration to provide unprecedented insight into how our local star ‘works’. Some are remote-sensing instruments that look at the Sun, while others are in-situ instruments that monitor the conditions around the spacecraft, enabling scientists to ‘join the dots’ from what they see happening at the Sun, to what Solar Orbiter ‘feels’ at its location in the solar wind millions of kilometres away.

The photo above, cropped, reduced, and revised slightly to post here, looks at the Sun’s south pole, from the side. The surface of the Sun (the top two thirds) almost looks like thunderheads on Earth, except the rain coming from them are high energy heat and radiation.

The data produced a lot of fascinating short movies, all available at the link, including a phenomenon the scientists have nicknamed a “space hedgehog” because of its look. About 15,000 miles across, “At present no one knows exactly what it is or how it formed in the Sun’s atmosphere.”

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Sunspot update: Sunspot activity continues to outpace predictions

3:23 pm

It is the first of the month, and NOAA has once again updated its monthly graph showing the long term trends in the Sun’s sunspot activity. As I do every month, I post it below, annotated with additional data to provide some context.

In March the Sun continued its unexpected high activity since the end of the solar minimum in 2020. The number of sunspots once again rose steeply, while also exceeding the predicted count for the month. The actual sunspot count for March was 78.5, not 34.1 as predicted. The last time the count was that high for any month was September 2015, when the Sun was just beginning its ramp down from solar maximum.
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Solar Orbiter takes closest image of Sun so far

10:18 am

Solar Orbiter's closest image of the Sun, so far
Click for full interactive image, where you can zoom in, a lot.

Cool image time! The European Space Agency (ESA) yesterday released several new images from its Solar Orbiter probe, taken when the spacecraft made its most recent closest approach of the Sun.

One of the images, taken by the Extreme Ultraviolet Imager (EUI) is the highest resolution image of the Sun’s full disc and outer atmosphere, the corona, ever taken.

Another image, taken by the Spectral Imaging of the Coronal Environment (SPICE) instrument represents the first full Sun image of its kind in 50 years, and by far the best one, taken at the Lyman-beta wavelength of ultraviolet light that is emitted by hydrogen gas.

The images were taken when Solar Orbiter was at a distance of roughly 75 million kilometres, half way between our world and its parent star. The high-resolution telescope of EUI takes pictures of such high spatial resolution that, at that close distance, a mosaic of 25 individual images is needed to cover the entire Sun. Taken one after the other, the full image was captured over a period of more than four hours because each tile takes about 10 minutes, including the time for the spacecraft to point from one segment to the next.

The photo to the right, reduced to post here, is the EUI photo.

Solar Orbiter has been in its science orbit since November, though that orbit over time will slowly be adjusted to swing the spacecraft into a higher inclination so that it can make the first close-up observations of the Sun’s polar regions. It is also working in tandem with the Parker Solar Probe, which observes the Sun from even closer distances using different instruments.

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Solar scientist Eugene Parker passes away at 94

2:53 pm

R.I.P. Solar scientist Eugene Parker, whose research revolutionized solar science in the 20th century and for which the Parker Solar Probe was named, has passed away at the age 94.

As a young professor at the University of Chicago in the mid-1950s, Parker developed a mathematical theory that predicted the solar wind, the constant outflow of solar material from the Sun. Throughout his career, Parker revolutionized the field time and again, advancing ideas that addressed the fundamental questions about the workings of our Sun and stars throughout the universe.

Parker belonged to the past generations of scientists who followed the principles of the Enlightenment and believed that science was fundamentally the search for truth. He understood he could always be wrong, which brought a certain muscular strength to any ideas he proposed. He could not be lazy in any way, or his work would fail. Instead, it shone, and made what little we know of the Sun today possible.

Sadly, such men are one-by-one going from us. I wonder if the new generations will understand his mindset.

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Sunspot update: The Sun rages on

10:54 am

Time for my monthly sunspot cycle update, where I take NOAA’s monthly graph showing the long term trends in the Sun’s sunspot activity, and annotate it with additional data to provide some context.

The trend of sunspot activity exceeding the predictions continued in February. While the increase in activity from January still left it less than the activity in December, the total number of sunspots is still far above the number predicted by NOAA’s panel of solar scientists in 2020, with the rise towards a solar maximum also much steeper and far faster than predicted.
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Sunspot Update: The Sun quiets down, but just a little

11:50 am

With the posting yesterday by NOAA of its monthly update to its graph showing the long term trends in the Sun’s sunspot activity, it is time for me to do my own update, showing this graph below with annotations in order to provide some context.

While sunspot activity dropped slightly in January, the activity still remained well above the prediction made by NOAA’s panel of solar scientists in 2020, with the upward trend towards a solar maximum much steeper than predicted as well.
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Sunspot update: The Sun blasts off!

10:16 am

Over the weekend NOAA posted its monthly update to its graph showing the long term trends in the Sun’s sunspot activity. As I do every month, I have posted that graph below, annotated to show the previous solar cycle predictions and thus provide context.

In December the Sun’s sunspot activity not only continued the pattern of the past two years — whereby sunspot activity has consistently exceeded the prediction of NOAA’s solar scientist panel — the amount of activity shot up like a rocket. December 2021 saw the most sunspots in a single month since September 2015, when the Sun was about a third of the way into its ramp down from the solar maximum in 2014.

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Scientists confirm Parker entered Sun’s corona in April 2021

9:40 am

Scientists yesterday announced that the Parker Solar Probe successfully entered the Sun’s corona for the first time during its April 2021 close fly-by.

More information here, including some excellent short movies made from images created by Parker’s instruments.

The top edge of the corona is dubbed the Alfvén surface, and Parker’s passage across that boundary three different times during the April ’21 fly-by revealed it to be a sharp boundary that also has a great deal of topography. From the second link:

The first time Parker passed the Alfvén surface was the longest; it flew through the atmosphere for about five hours. Even as it continued flying toward the Sun, though, it popped back out, only to submerge again more deeply when it was at its closest approach — but briefly, that time exiting after just half an hour. Then, on its way outward, the spacecraft once again skimmed beneath the surface for a few hours.

“[The Alfvén surface] has to be wrinkly,” Kasper says. “It’s not fuzzy — it’s well-defined while we’re under it — but the surface has some structure to it.” So while the probe sees a smooth change in conditions while crossing the boundary, where the boundary is can change. The reason for this wrinkly surface is still an open question, though the researchers suspect the crossing over a pseudostreamer lower in the corona pushed the boundary out to enable the first crossing.

What’s clear is that inside the Sun’s atmosphere, conditions are different than just outside. Parker saw plasma waves moving back and forth instead of flowing outward. That difference was visible not just to the SWEAP and FIELDS instruments, which measure particles and electric and magnetic fields, respectively, but also to the probe’s WISPR imager.

The Parker science team also indicated that the preliminary data from the probe’s next two fly-bys — the most recent in November that was the closest yet — suggest it passed through the corona then as well.

One of the biggest unsolved mysteries about the Sun’s corona is that it appears to have a temperature in the millions of degrees, far hotter than the Sun’s surface below, something that is counter-intuitive. The expectation was that the atmosphere would be cooler than the surface. Finding out why the corona is hotter is one of the main science goals of Parker. It appears the probe is finally gathering data that might help solve that mystery.

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Sunspot update: Sun continues to be more active than predicted

12:45 pm

Time for our monthly sunspot update, using NOAA’s most recent monthly graph of sunspot activity. That graph is below, annotated to show the previous solar cycle predictions and thus provide context. It covers all activity through the month of November.

The pattern for the past two years since the end of the solar minimum continues, with sunspot activity consistently exceeding the prediction of NOAA’s panel of solar scientists, as indicated by the red curve. The activity in November dropped very slightly from October, but remained more active than the prediction.

» Read more

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