The
Great North American Eclipse!
Welcome
to the total solar eclipse of 08Apr24
(Sorry, not visible in India)
“If
you're outside the path of totality of eclipse, if there's any way you can get
into the path of totality for the eclipse, do it. Take the day off. Take the
kids out of school. This is a once-in-a-lifetime opportunity for most people to
see a total eclipse, and it is one of the grandest sights in all of nature.
It's something you'll always remember, and you'll pass stories of it onto your
grandchildren.”
- Fred Espenak
[As
I get ready to journey half way around the globe to the USA to chase this, the
fifth total solar eclipse since my inaugural one in 1980, I am writing this as
a welcome message to what should be yet another fabulous astronomical event.]
Alas! The exhortations of Fred Espenak, the great eclipse chaser and inveterate ‘computer’ of eclipses for NASA, will have to be ignored by everyone in India, and indeed in the whole of the eastern hemisphere, because the entire path, let alone the much narrower and crucial path of totality, of this rare total solar eclipse, is confined solely to the western hemisphere (Mexico, the USA and Canada). However, the really significant part of its progression can be followed live in India for about an hour on Monday, 08th April 24 from 23:15 to Tuesday, 09th April 24 around 00:15 (approximate times), with the maximum occurring around 23:47, on several online channels, including:
https://www.timeanddate.com/live/eclipse-solar-2024-april-8
Solar
Eclipses
First,
let me review what solar eclipses are. The following text is adapted from one
of my earliest blog articles on eclipses (see here):
Eclipses
of the Sun and the Moon as viewed from any place on Earth are possible only
because of a fortuitous and accidental circumstance associated with the Sun and
the Moon. While the Sun is about four hundred times bigger than the Moon, it is
also nearly as many times farther away from the Earth as is the Moon.
Therefore, they appear to be of nearly the same apparent size (about 0.5 degree
in angular diameter) as seen from the Earth. On the occasions when these three
bodies are nearly in a line, solar or lunar eclipses, which may be partial or
total, are possible. A partial solar eclipse results when the lunar disk hides
only a portion of the solar disk on a new moon day. A total solar
eclipse happens when the lunar disk is slightly larger than the solar disk and
blots it out of sight from the earth at the viewing site, revealing
the spectacular sight of the solar corona, which can be viewed with the naked
eye. An Annular Eclipse results if
the lunar disk is slightly smaller than the solar disk and a thin peripheral
ring of the Sun can still be seen at maximum eclipse.
Total
and annular solar eclipses are extremely rare events at any specific
place on earth and last only a few minutes at most. For the
duration of a total solar eclipse, day turns nearly into night and produces
some breathtakingly beautiful effects, justifying Fred Espenak’s exhortations
cited above.
With
reference to the diagram below, total and annular eclipses are possible at
locations in the umbral and antumbral shadow regions, and partial ones outside
of them, in the penumbral shadow regions.
Rarity
of Total and Annular Eclipses
From the
relative motions and sizes of the Sun, the Moon and the Earth, one can show
that total and annular solar eclipses can occur, on the average, about once in
eighteen months, and hence they are not really infrequent. However, considering that the surface of the
globe is predominantly water, and populated land area is relatively small, few
of them end up stirring popular interest. The narrow path of the eclipse, the
width and extent of totality, and its short duration, all ensure that fewer
still are of non-academic interest. The probability that a viewer gets to
witness one such eclipse at any specific location is estimated to be
once in about 375 years! This makes these events truly rare and one may not
even get a chance to see even one total eclipse in one’s lifetime. This means,
a serious observer will have to travel to where the event happens, rather than
wait for it to happen, and many a time this means travelling large distances to
far off places. For me, next month’s
eclipse means a journey half way across the globe, just like the last one in
2017!
Totality
For a thoroughly detailed and graphic description
of the unique experience of totality, I can do no better than to quote Mark Littmann, Fred Espenak and Ken
Willcox from their book The Experience of Totality, first published in
2008:
First contact. A tiny
nick appears on the western side of the Sun. The eye detects no difference in
the amount of sunlight. Nothing but that nick portends anything out of the
ordinary. But as the nick becomes a gouge in the face of the Sun, a sense of anticipation
begins. This will be no ordinary day.
Still,
things proceed leisurely for the first half hour or so, until the Sun is more
than half covered. Now, gradually at first, then faster and faster,
extraordinary things begin to happen. The sky is still bright, but the blue is
a little duller. On the ground around you the light is beginning to diminish.
Over the next 10 to 15 minutes, the landscape takes on a steely gray metallic
cast.
As
the minutes pass, the pace quickens. With about a quarter hour left until
totality, the western sky is now darker than the east, regardless of where the
Sun is in the sky. The shadow of the Moon is approaching. Even if you have
never seen a total eclipse of the Sun before, you know that something amazing
is going to happen, is happening now--and that it is beyond normal human
experience.
Less
than fifteen minutes until totality. The Sun, a narrowing crescent, is still
fiercely bright, but the blueness of the sky has deepened into blue-gray or
violet. The darkness of the sky begins to close in around the Sun. The Sun does
not fill the heavens with brightness anymore.
Five
minutes to totality. The darkness in the west is very noticeable and gathering
strength, a dark amorphous form rising upward and spreading out along the
western horizon. It builds like a massive storm, but in utter silence, with no
rumble of distant thunder. And now the darkness begins to float up above the
horizon, revealing a yellow or orange twilight beneath. You are already seeing
through the Moon's narrow shadow to the resurgent sunlight beyond.
The
acceleration of events intensifies. The crescent Sun is now a blazing white
sliver, like a welder's torch. The darkening sky continues to close in around
the Sun, faster, engulfing it.
Minutes
have become seconds. The ends of the bare sliver of the Sun break into
individual points of intense white light--Baily's Beads-- the last rays of
sunlight passing through the deepest lunar valleys. Opposite the crescent, a
ghostly round silhouette looms into view. It is the dark limb of the Moon,
framed by a white opalescent glow which creates a halo around the darkened Sun.
The corona--the most striking and unexpected of all the features of a total
eclipse--is emerging.
Almost
instantaneously, the incredibly thin crescent Sun fragments into a series of
brilliant beads and short arcs which dwindle and vanish in rapid succession.
And now, there is only one bead, set like a single dazzling diamond in a
ring."
But
its penetrating brilliance rapidly fades as if it were sucked into an abyss.
Totality!
Where
the Sun once stood, there is a black disk in the sky, outlined by the soft
pearly white glow of the corona, about the brightness of a Full Moon. Small but
vibrant reddish features stand at the eastern rim of the Moon's disk,
contrasting vividly with the white of the corona and the black where the Sun is
hidden. These are the prominences, giant clouds of hot gas in the Sun's lower
atmosphere. They are always a surprise, each unique in shape and size,
different yesterday and tomorrow from what they are at this special moment.
You
are standing in the shadow of the Moon.
It is dark enough to see
Venus and Mercury and whichever of the brightest planets and stars happen to be
close to the Sun’s position and above the horizon. But it is not the dark of
night. Looking across the landscape at the horizon in all directions, you see
beyond the shadow to where the eclipse is not total, an eerie twilight of
orange and yellow. From this light beyond the darkness which envelops you comes
an inexorable sense that time is limited.
Now, at the midpoint in
totality, the corona stands out most clearly, its shape and extent never quite
the same from one eclipse to another. And only the eye can do the corona
justice, its special pattern of faint wisps and spikes on this day never seen before
and never to be seen again.
Yet around you at the
horizon is a warning that totality is drawing to an end. The west is
brightening while in the east the darkness is deepening and descending toward
the horizon. Above you, prominences appear at the western edge of the Moon. The
edge brightens.
Suddenly
totality is over! A brilliant bead of sunlight appears. This heavenly diamond
quickly grows into a band of several jewels which merge together to form the
returning crescent Sun. The dark shadow of the Moon silently slips past you and
rushes off toward the east.
Total
vs Annular vs Partial
Both total and
annular eclipses arise from the same relative dispositions of the three
celestial objects – the Sun, the Moon and the Earth. During a total eclipse the
solar disk is completely covered by the lunar shadow. During an annular
eclipse, the lunar shadow is not large enough to do so and this results in a
ring of bright solar light, popularly called the ‘ring of fire’, visible to the
viewer at eclipse maximum. Except for
this interesting visual effect, the annular eclipse is hardly different from a
partial eclipse. In neither case does daylight disappear fully to make way for
a night-like experience, for whatever duration.
For this reason, annular eclipses as well as partial ones are far from being
the extraordinary visual spectacles that total eclipses are.
During a total eclipse, some people living just
outside the belt of totality are satisfied with observing an eclipse just under
100% rather than travel a few kilometers that takes them inside the belt for a full
100% view, however brief. Sadly, they
are missing the sight of a lifetime since nothing short of a 100% eclipse
produces the unique
sequence of effects that begin to unfold rapidly at the onset and just before
the end of totality. Looking at even a 99% partial eclipse is like looking at
an empty nest without its occupant.
In actual fact, travelling into the belt of
totality doesn’t guarantee a successful observation of a total
eclipse. However carefully the observing
location may have been chosen, luck also plays a significant role in one’s
success. This is because of the vagaries of weather; even a hovering cloud may
blot out the Sun during the short period of totality and spoil the view irretrievably.
My
tryst with solar eclipses
The first
total solar eclipse I viewed was on 16 Feb 1980 from the Tungabhadra Dam site
in North Karnataka, India. Visible on an
absolutely clear blue afternoon sky, it was a sight that has lived permanently
etched in my memory, as are the ones that followed. I have described it in my inaugural blog here, on its
thirtieth anniversary. After that, there
was an inexcusable hiatus until my second one, in a beautiful place near
Hangzhou in far off China, on 22 Jul 2009.
The fact that it was partially affected by the much-dreaded clouds was
mitigated by its exceptionally long duration of totality, lasting 5 min 40 sec
where I observed it. I have described the event in considerable detail, along
with my adventures both before and after, in my blog here. Below is a
photograph of me with my observing gear consisting of just a pair of 7x50 binoculars
mounted on a mini tripod:
My third one
was in the coastal city of Palu in Central Sulawesi Province of Indonesia, on
09 Mar 2016, another exceptionally beautiful event in a great setting close to
the central line of totality. It is saddening to recall that Palu was devastated
a few years later by a strong earthquake, followed by a tsunami, wreaking great
destruction of life and property. Here
is a picture of me with my observing equipment being given a thumbs-up by a
Finnish tourist and eclipse enthusiast at the eclipse festival that had been
organized concurrently at Palu to commemorate the event:
In a recent
blog article (see here), I have
touched upon my memorable experience with the annular solar eclipse of
26 Dec 2019 observed with a close-knit group of associates and friends at the
coastal town of Bekal in north Kerala. Here is a picture of me and some of the
members of my group as we waited for the annularity to set in:
Previously, I
had written about the great annular eclipse of 15 Jan 2010 (see here) which I had
observed from Dhanushkodi, overlooking Sri Lanka, in the Rameshwaram district
of Tamil Nadu.
I have been particularly lucky in having been
able to see all six of the events I have observed so far in different
countries, including two in India, totally successfully. I hope that in future not
only my opportunity but also my luck continues to stay with me.
Eclipses and USA
Incidentally, the USA happens to be the rich ‘beneficiary’ of as many as three great solar eclipses within a short period of seven years, from 2017 to 2024. All three of them touch large areas of continental USA as the respective maps indicate. The first one, on 21 Aug 2017, was a total solar eclipse that could be seen over a vast stretch of land spanning from the northwest to central east (see map below).
The second is the annular eclipse of last year,
on 14 Oct 23 (see map below). It has
been described in a previous blog article (see here)
though I had to give it a go bye for reasons outlined in my write-up.
The third one is the forthcoming total solar eclipse of 08Apr24, the
subject of the present article.
Eclipse of 08Apr24
The eclipse on 08Apr24 encompasses the largest area of populated land
ever, stretching from western Mexico, through a vast swathe of continental USA
up north and northeast, and into the southeastern part of Canada as can be seen
from the following NASA map:
Below is an animation showing the umbral (thick central) and penumbral
shadows of the Moon sweeping over the north American continent on 08Apr24. A
total eclipse will be visible at all points lying on the umbral shadow region.
I also consider it pointless to go to a far-off
place just to see an eclipse however unique it may be. To get the best out of
the visit, one has to make it part of a much longer tourist trip. I
did that in 2017, making the eclipse visit as a part of a long three-week trip
to USA, and then on to Europe for another three weeks. This time I will be
restricting myself to North America, visiting Mexico and Canada besides the
USA, on a five-week trip.
Epilogue
For eclipse chasers, less
popularly known as umbraphiles, the name of Dr Fred Espenak stands out like
a legend. More popularly known as “Mr Eclipse”, he was until recently the human
brain behind all the eclipse predictions made for NASA. Now a retired Emeritus
astrophysicist, he
became interested in astronomy when he was 7–8 years old, and had his first
telescope when he was around 9–10 years old.
The first eclipse he saw was on 7 March 1970, which sparked his interest in
eclipses, and he has since seen as many as 30 of them, far more than most
eclipse chasers can boast of. He is the
co-author of a notable recent work on solar eclipses titled Totality
(see picture below showing him together with the title page of the publication).
The following quote is attributed to Espenak in
this publication subtitled, ‘The Great North American Eclipse of 2024’:
“In rating natural wonders, on a
scale of 1 to 10, a total eclipse of the Sun is a million.”
I would have agreed with this assessment until last October when I saw
the dense central core of the Milky Way galaxy with the naked eye at the Hanle
Dark Sky Reserve in the Himalayas of Eastern Ladakh, India. If anything could outdo my eclipse experience, this was it. I rate it just a wee bit higher, at a million plus one!
