Total Solar Eclipse 2017

Are you using Whatsapp and did you recently receive this picture? Getting excited already, that in a few weeks time you will observe a unique event?

Sorry to disappoint you, but this is complete nonsense. Yes, on 21 August 2017 there will be a total solar eclipse, and to watch it is an experience of a lifetime. But solar eclipses are common, almost every year there will be a solar eclipse visible, somewhere on Earth..:-)

Here is a list of solar eclipses between 2011 and 2020. In the third column the type of eclipse is given. Twenty four eclipses in total, five of them total. The last column gives the geographic region where the eclipse will be visible.

I do not want this blog to be very technical, but some explanation may be useful..:-)

A solar eclipse occurs when the moon passes between the sun and the earth.

The moon orbits the earth in about 29 days, so you would expect a solar eclipse roughly every month. But the orbital plane of the moon is tilted 5 degrees, therefore the shadow of the moon will not touch the earth every month. Also, because of the (big) size of the sun, the shadow of the moon (the white lines) just reaches a small part of the earth. The pink lines mark the region where the moon blocks the sun only partially.

Another effect is that the orbit of the moon is slightly elliptical, so the distance of the moon to the earth is not always the same. If the moon passes between the sun and earth while it is farther away from the earth, it can not block the sun completely, resulting in an “annular” eclipse.

Let us look in a bit more detail at the 21 August eclipse. The blue band is where you can see the total eclipse. Weather permitting of course…:-) The light blue lines parallel to the blue band indicate the regions where you have a 75%, 50% and 25% partial eclipse.

Is there anything special about this eclipse? Yes..:-)  It will only be visible from the Unites States of America and no other country!  AMERICA FIRST…:-)  Probably Trump will  twitter one of these days that it is one of the successes of his administration…;-)

Of course there is a lot of interest in the USA for this Great American Eclipse . Here are a few advertisements, taken from the Internet.

But also for the USA it is not a unique event. The last total eclipse, visible in mainland USA, was on 26 February 1979 and the next one will be on 8 April 2024.

Total eclipses are spectacular. It gets dark, and the solar corona becomes visible. A reason for many people to travel to a region where the total eclipse can be watched.

Actually I was one of them, 8 years ago!

Friends  told us about a total eclipse, visible in China on 22 July 2009.  Here it is

We decided to visit China, Hangzhou region, around that time, hoping for clear skies. The full report you can read here: China July 2009 part I: Hangzhou.

Many people, locals and tourists,  full of expectation.

Actually it was rather cloudy. Here you see pictures during the start of the eclipse. We kept our fingers crossed.

And we were lucky. The clouds were breaking, it was not completely clear, but enough to see the “diamond ring” and the corona

It was an unforgettable experience. As it will be for the Americans (and the many foreign tourists) on 21 August.

When you compare the two eclipse maps, you see in the lower right corner the duration of the totality.  The China one 6m 39s, the American one “only” 2m 40s. CHINA FIRST!

The maps come from a very informative website about solar (and lunar) eclipses,

Our Solar system, an update

My last blog about the Rosetta, Dawn and New Horizon missions was posted in July last year. Before I give an update, let’s first have a look at our Sun. Here is a recent graph of the number of sunspots. Cycle 24 has reached a maximum in April 2014 and is coming to an end.


As you will notice, cycle 24 has a double peak, in itself not unusual, but this time the second peak is higher than the first one. The maximum of cycle 24 is much smaller than that of cycle 23, and the prediction for cycle 25 is that it will be similar to cycle 24 or even smaller.

Here is a graph of the sunspot cycles, recorded until now. It looks like we have passed the Modern Maximum and are going to a minimum. Are we heading to a new “Little Ice Age“?  As I wrote in an earlier post, this is a sensitive issue, and I will not comment on it..:-). Be very wary when you search the Internet for info  about a relation between solar activity and global warming. Always check the credentials of the report. You might try this site: Skeptical Science


Here is a dramatic image of our Sun, taken by the Solar Dynamics Observatory. Magnetic field lines are superimposed.



Rosetta is still orbiting comet 67P, which has passed its perihelion and is now on its way out into deep space. Here is the position of Rosetta and the comet, end of last year, the comet has passed already the orbit of Mars. No signals of the comet lander Philae have been received anymore, but Rosetta itself is still active.


Here is a recent image of 67P, taken on 27 March, when Rosetta was 329 km away from the comet nucleus. The Sun is behind the comet, with a spectacular result.


The scientists are planning to let Rosetta make a controlled landing on 67P in September 2016, which will be the end of the mission. You can find the latest news on Rosetta’s blog


Dawn is still in orbit around dwarf planet Ceres. Slowly getting closer, resulting in more detailed pictures. You may remember the excitement about the bright white spots. Now we know that they are located in the center of a crater, which has been given a name: Occator. More (smaller) white spots have been found


Here is the most recent picture (in false color), taken 30-3-2016 from an altitude of 385 km. . Spectacular. Scientists now think that the white spots are formed by highly reflective material, possibly ice or salt.


Actually Dawn is taking pictures of the whole surface of Ceres. Scientists have been busy giving names to the various features..:-)

Ceres mapping

For more information about Dawn, read this detailed blog So.Much.Ceres, published a few weeks ago

New Horizons

On 14 July 2015, the New Horizons spacecraft passed Pluto at an altitude of 12.500 km above its surface. It took as many pictures during the fly-by (of only a few minutes!) as possible and it still has not finished transmitting all the data to Earth!

Here is one of the images, released a few days ago. It shows numerous “haloed” craters. The false-color image gives the composition: purple is methane ice, blue is water ice. Why the crater rims and walls consist of methane ice has not yet been explained.

Craters on PLuto

New Horizons is now on its way to the Kuiper Belt, where it is supposed to flyby one of the Kuiper Belt objects, 2014 MU69 , on 1-1-2019.  Here are the present locations of the New Horizons spacecraft and 2014 MU69


Planet 9

We have reached the outskirts of our Solar System. Pluto, once the 9th planet, has been demoted and is now considered a dwarf planet belonging to the Kuiper belt. Recently more dwarf planets have been discovered in the region beyond Neptune,  Eris ( in 2005) , Haumea (in 2004) and Makemake (in 2005)  Like Pluto they have quite elliptical  orbits and periods in the range of a few hundred years. Pluto for example has a period of  248 year and its distance to the Sun varies between 30 and 49 AU, where 1 AU (the average distance between Earth and Sun) = 150 million km. The orbits of these dwarf planets have been strongly influenced by big neighbour Neptune.

In 2003 dwarf planet Sedna was discovered with an estimated period of 11.400 year and a distance to the sun varying between 76 and 936 (!) AU. Here is the orbit of Sedna. Pluto’s orbit is purple.


What could have caused such an extremely elliptical orbit? It can not have been gravitational disturbance by Neptune, because it never comes close to Neptune (distance of Neptune to the Sun is 30 AU).

In the last decade more of these “strange” objects have been discovered. For example in 2012  2012 VP113, estimated period 4200 year, distance to the Sun between 80 and 438 AU, also very elliptical.  Here the orbits of six of them are given.


Could these orbits be gravitationally disturbed by an UNKNOWN planet in the outer reaches of the Solar system?

On 20 January 2016 astronomers Brown and Batygin published an article in the Astronomical Journal: Evidence for a distant giant planet in the Solar System (abstract). Using computer models, they find that a planet with a mass about 10 times the mass of Earth, a period of 10.000-20.000 year, and a distance to the Sun varying between 200 and 1200 AU, could explain the orbits. Tentatively this planet is named Planet Nine .

Here is a sketch with the position of this Planet Nine.


Of course this is a hypothesis until now. Other explanations are possible. Next step is to try and find Planet Nine. That will not be easy, even for the most powerful telescopes. And where to look for it?

Here is a picture of the two authors, both astronomers from Caltech. By the way, Brown (left) is  the guy who discovered Eris, which started the demotion process for Pluto!

Brown & Batygin

They have started a website The Search for Planet Nine and just submitted a (highly technical) paper in which they discuss where to search for this planet.

If Planet Nine is ever found, I will not be surprised if they get a Nobel Prize for their research.

Our Sun again

It is almost one year ago that I gave you an update about the Solar Sunspot Cycle 24. For those who have not read those earlier posts, a short recapitulation.

Sunspots are dark spots on the surface of the Sun and related to the sun’s magnetic structure. It is a periodic phenomenon, sometimes there are many, sometimes there are almost none at all. The period is about 11-12 years, and one such a period is called a Sunspot Cycle.


This periodic behaviour was discovered in 1843 by Schwabe, a German astronomer. Rather arbitrarily a numbering was introduced, with cycle 1 lasting from 1755 until 1766. We are now at the maximum of cycle 24. In the picture below the ‘average’ number of sunspots is shown as a function of time, for cycle 23 and 24, updated until November 2013

Cycle 23 and 24

As you see, the maximum is considerably lower than the maximum of cycle 23. And that is the reason that I have published my earlier posts, for example Don’t worry, our Sun is not dead. You can read more background information there.

Here is a graph showing you the large variation in these sunspot maxima during the last 500 years. In the last 50 years the sunspot activity has been unusually high, whereas in the second half of the 17th century there was hardly any activity at all. This period is called the Maunder Minimum, whereas the last 50 years are sometimes called the Modern Maximum. Another period of low activity occurred in the beginning of the 19th century: the Dalton Minimum.


So now the burning question is: are we on our way to a new minimum 

The picture above I have used already in my post, one year ago, How is the Sun doing these days? At that time the prediction was that the maximum would be about 76 and I had marked this maximum with a red cross, comparing it with the low value of 64 in 1906. Now, one year later, we have reached the maximum and it is even lower than predicted, ~ 65 (red circle). Although it is a bit early, a few predictions have been made already for cycle 25, which will peak around 2024. Peak may not be the right word, because the maximum might be as low as 7!

If we are going to a new minimum, will it be Dalton-like or Maunder-like? No one can tell at this moment. We do not really understand much of the underlying mechanism. When we study the Sun in visible light, it looks peaceful, with occasionally a few spots..:-). But look at the Sun in the ultraviolet region, and you see how violent it is.

solar images

Is there a relation between the periods of large/small solar activity and the climate on Earth? During the  Maunder Minimum we had the Little Ice Age.  Is the Global Warming fully due to the hothouse effect of carbon dioxide, or has the Modern Maximum also its influence? This is a sensitive topic, that I will not touch. The next decade we will hopefully learn more.

For more information, here is a very readable article in Sky and Telescope (published already two years ago): Is the Sunspot Cycle About to Stop?

Doomsday 2012 and the Sun

The Mayan Long Count calendar ended on 21-12-2012. Actually it did not really end, but a new cycle started on that date. So 21-12-2012 can be seen as Mayan New Year’s Eve. The next one will be on 26-3-2407.

Quite a few people expected that the world would end on this day. Sad. Suddenly Nibiru would show up behind the moon and destroy Earth, or the magnetic field of Earth would suddenly reverse, etc.

Here is a picture of the Sun, apparently taken just after “Doomsday”. It looks like the Sun is winking…:-). The picture comes from a recent newspaper article, personally I doubt if the picture is authentic, especially the “lips” I find suspicious.

Doomsday Sun

In the past I have published several posts about the Sun. It will reach a maximum in its 11-year sunspot cycle, next year. It is becoming clear now that this maximum will be very low. Here is a picture updated until December 2012.


The expected maximum of around 72 will be the lowest since 1906. Nevertheless Michio Kaku , the physicist “who would kill his mother to get publicity” (quote by me, LOL) is warning about solar storms that might create havoc on earth.

How is the Sun doing these days?

My last post about the Sun is from August 2010. At that time it had become clear already that the present Solar Cycle 24 would be a weak one. We are now two years further, the maximum in solar activity is expected around September next year. Time for an update.

Here is the most recent prediction, with data points until September

The current prediction is a (smoothed) sunspot number maximum of about 76. That is low! We have to go back to Cycle 14 in 1906, to find a lower maximum value of 64.

Here is a graph of the Solar Cycles over the past four centuries. With red crosses I have marked the 1906 maximum and the (predicted) 2013 maximum.

You will notice that the last half century we have had a “wave” of solar activity. Is that coming to an end now and will we enter a period of low solar activity? Nobody knows, as we do not understand very well the origin of the Solar Cycle.

Both the Maunder minimum (17th century) and the Dalton minimum (~ 1800) had influence on the Earth climate. Severe winters in Europe as can be seen in paintings of the Dutch School, like this famous one by Hendrick Avercamp (1585-1634)

Now we live in a period of global warming. There are strong indications that our carbon emission is at least partly responsible for this. But could there also be a contribution due to the high solar activity during the last fifty years? Those are sensitive questions..:-)

How is our sun doing these days? An update

End of March I have added a post about the (lack of) sunspot activity on the Sun.
Solar cycle 24 was so slow in starting, that some scientist got worried.
What is the present situation? See the graph below. Four more data points became available (April-July). The graph comes from
The red curve is a prediction, made in 2009.
The authors write:
If our prediction is correct, Solar Cycle 24 will have a peak sunspot number of 90, the lowest of any cycle since 1928 when Solar Cycle 16 peaked at 78

When you look at the latest data points, the prediction seems too high, it should be adjusted.
Actually this has been done last month, see below. This new prediction gives an even lower maximum, below 70 !!

If this prediction comes true, we even have to go back to solar cycle 14, with a peak value of  64, in 1906. Click here for the list of solar cycles.
You can bet on it that solar scientists are following the development with great interest.
I will give you another update in a couple of months.

Don’t worry, our sun is not dead!

As you know, the sun is our life source..:-)
Already for more that 4.5 billion years she (or is it he?) is providing the energy for our solar system and she will continue to do so for another 5 billion years, before she will “die” and end as a so-called white dwarf
So why did the well-known Dutch solar astronomer Kees de Jager remark in an interview, November 2009, that the sun was dead?

Well, he was talking about the sunspot activity of the sun. Or rather, the lack of sunspot activity!

Here is an image of the sun, with a number of sunspots

Sunspots are a result of magnetic activity on the sun. The number of sunspots fluctuates in time with a period of roughly 11 years.
See the graph below. It is clear that it is a periodic phenomenon, but also that it is quite irregular.
The cycles are numbered from the time accurate observations became available, around 1750.
Cycle 23 started in 1996, reached its maximum around 2002, ending in 2007.
At about that time, 2007-2008 the new cycle 24 was expected to start.

But it did NOT!

During 2008 and 2009 the sun was surprisingly quiet, with long periods without any sunspots at all.
Therefore astronomers all over the world were watching the sun with more than usual interest.
A special website is monitoring daily the behaviour of the sun.

Here is a detailed graph, updated until February 2010. The red curve is the expected one.

As you see, 2008 and 2009 have been very quiet, with the average sunspot number almost approaching zero.
BUT, starting from December 2009 it looks like we have the beginning of cycle 24! Finally.
In a couple of days the results for March will be published. You can check for yourself:

Is this topic only of academic interest?
There may be a relation between the solar activity and the temperature of Earth.

Here is one more graph of the solar sunspot activity, this time over a time period of 400 years. In 1610 sunspots were observed for the first time with the newly invented telescope.
The red crosses represent these early observations. They are less accurate, but nevertheless it is obvious that in the second half of the 17th century there were hardly any sunspots at all.
This dip in solar activity is called the Maunder Minimum.


In the same period Europe and North America (and probably the rest of the world) were subjected to very cold winters, this period is called the Little Ice Age
There is an ongoing debate if there is a causal connection.
The last 50 years there has been a maximum in sunspot activity. Could it be that this increased activity has been another factor in the global warming, besides carbon emission?