Annular Solar Eclipses 

Eclipse path on 14 Oct 23 confined to the Americas

I had read all I could about solar eclipses, but I was quite unprepared for the experience of totality. It was electrifying, sublime, awesome and humbling all at the same time.

- Fred Espenak

 

 

Path of annularity

Prelude

A spectacular annular solar eclipse is due next Saturday (14th October 2023).  It will be confined solely to the western hemisphere and visible in large parts of the American continents as can be seen in the graphic above.

The excitement expressed by Fred Espenak, the great eclipse chaser and inveterate ‘computer’ of eclipses for NASA, is applicable to a total solar eclipse, not as much to an annular eclipse like the one due on the 14th of this month.  It will still be a memorable experience if one is located anywhere on the path of annularity.  In any case, it will have to be ignored by everyone in India, and indeed in most parts of the world, because the entire path, let alone the much narrower and crucial path of annularity, covers a different part of the globe. 

Apart from describing the forthcoming annular eclipse in the context of solar eclipses in general, and two eclipses due within a short span of each other in the USA in particular, I take this opportunity to recount my earlier experience with two annular eclipses that I have viewed, both in India.

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 Espenak’s exhilaration cited above. In contrast, a part of the sunlight gets through at all times of an annular eclipse, even at the peak of annularity, and to that extent it is still daylight. However, the brightness of the sunlight getting through depends on the fraction of the sun’s disc obscured, and it will be a minimum during the peak of the annularity phase. In any case, it would be dangerous to look at an annular solar eclipse with the naked eye, as also a total one, except during the very brief period of totality when the Sun is completely obscured.

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. 

[From nineplanets.org]

Annular Eclipse of 14 Oct 23

The really significant part of the progression of this annular eclipse can be followed live on Saturday, 14th October 2023 from 9:00 PM to 11.30 PM (approximate times), with the maximum occurring around 10:24 PM, on several online channels, including:

https://www.timeanddate.com/live/eclipse-solar-2023-october-14

Below is a map of the USA showing the path of annularity in relation to some of the prominent geographical locations. The map also shows the appearance of the Sun at maximum eclipse at locations outside the path of annularity where the eclipse is only partial, and nowhere as attractive to observe as within the path of annularity. 

Path of annularity of 14Oct23 Eclipse

Below is a simulation of how the ‘ring of fire’ produced by the visible part of the Sun around the lunar disc will appear at a place like San Antonio in Texas.

Two recent annular eclipses

Besides a few total solar eclipses, I have had the opportunity to view two annular solar eclipses, both of them in recent times and within India. The first one, on 15 Jan 2010, viewed from Dhanushkodi in Tamilnadu, has been described in detail in one of my blog articles (see here). Here is a sequence of pictures taken at that time: 

During the peak of the annularity phase that lasted over ten minutes (the longest this millennium!), the ‘ring of fire’ was a nearly perfect ring alright, but such a large fraction of the solar disc was still visible that the resulting drop in brightness was barely noticeable!

The more recent annular eclipse that I viewed, along with a group of associates and friends, was on the morning of 26th December 2019 at Bekal Beach near Kasargod in Kerala state.  Here is a set of unedited pictures sent over WhatsApp and headlined by the local ‘Star of Mysore’ newspaper the same evening: 

Apart from photography, we made it possible for a large number of onlookers to view different phases of the eclipse by projecting an image of the eclipsed Sun on a white screen using a small telescope.  Here is a treasured picture of my colleague Mr Krishnamurthy focusing the image at the peak of the annularity phase:

The fraction of solar disc visible in the above picture is much smaller than the one in the annular eclipse of 15 Jan 10, yet the surroundings are bright* enough for shadows to be visible clearly, as also the onlookers.  This is the reason why an annual eclipse is almost always much less impressive visually than a total one.

[*Note:  An important parameter associated with eclipses is its magnitude, which is the fraction of the angular diameter of the celestial body being eclipsed, in this case the Sun.  For the annular eclipses of 15Jan10, 26Dec19 and 14Oct23, the magnitudes are 0.919, 0.970, and 0.952 respectively.  Clearly, the forthcoming eclipse promises to be no more spectacular than the one in 2019.

On the other hand, the annular eclipse of 21Jun20, visible in parts of northern India, had a magnitude of 0.994. A small group of us were to have witnessed it in Suratgarh, Rajasthan, but unlucky to miss out the trip because of travel restrictions due to the Covid pandemic. From descriptions of those who did view it, I understand it was pretty much like a total eclipse lasting just a few seconds.]

 USA – Eclipses in Quick Succession

The USA is 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 vast 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 forthcoming annular eclipse that is the topic of this article. 

Total Solar Eclipse of 21 Aug 2017

The third is another great total solar eclipse that is due next year on 8th April, again covering a vast stretch of the country, and beyond, as the following map indicates: 

Total Solar Eclipse of 08 Apr 2024

If the two previous maps are superposed, we end up getting the following composite map showing both the paths, and very interestingly, their intersection as well.

The intersection, shown magnified in the following map, tells its own story: 

The huge state of Texas finds large parts of its territory covered by both eclipse paths, which means anyone in such a location (in the large city of San Antonio for example) can see both eclipses within a span of six months.  Probabilistically, the waiting period for any specific location on earth experiencing such consecutive eclipses is estimated to be around 375 years!

Personal regrets

Three great solar eclipses within a span of less than seven years meant both an opportunity and a challenge for me, challenge because any place in USA is as far away from my home as it can get, with the consequent drain on my resources. It is 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 a successful visit to Nashville, Tennessee, to view the total eclipse as a part of a long trip to USA and then on to Europe. 

Now, I find myself unable to visit USA twice within a span of six months and needing to settle for only one visit.  For this reason, I am regrettably opting out of the forthcoming annular eclipse in favour of a more spectacular total one on 8th April next year, somewhere north of Austin, Texas.  Naturally, I intend to make it part of a longer trip, including Mexico and Canada apart from USA.

The bottom line

Apart from the generally very short duration, the rarity of total or annular solar eclipses at or near any particular location on earth means that we may be lucky to see one in an entire lifetime.  The rarity is compounded by the vagaries of weather, especially cloud cover, at the time of totality or annularity, which may spoil the best part of the show completely and make the journey almost worthless.  However carefully the observing location on the central path of the eclipse may have been chosen, luck also plays a significant role in one’s success. 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 not only my opportunity but also my luck continues unabated.  

 

 

World Space Week, October 4-10

Space and Entrepreneurship (2023)

 

Entrepreneurship is the ability and readiness to develop, organize, manage and run a business enterprise, together with any attendant risks and uncertainties, in order to make a profit. One of the best examples of entrepreneurship is the starting of a new ‘start-up’ enterprise.

The theme for World Space Week 2023, ‘Space and Entrepreneurship’, “recognizes the growing significance of the commercial space industry in space, and the increasing opportunities for space entrepreneurship and new benefits of space developed by space entrepreneurs. With miniaturization and decreasing launch costs, it is now possible for a small business to build and launch a small satellite, and for entrepreneurs to create valuable new data products for governments and industry.”

Dawn of the Space Age

October 4, 1957 is a red-letter day in human history.  It marked the dawn of the Space Age with the launch of the first human-made Earth satellite, Sputnik 1, thus opening the way for space exploration.  Mostly the stuff of science fiction till then, and conceived by Newton in his celebrated Principia Mathematica as far back as 1687, this achievement was possible through rapid advances in multi-stage rocket technology that made it possible to place instrument bearing satellites in earth orbit initially, and humans subsequently.  Another icon of science fiction, the communication satellite, predicted by science communicator Arthur C Clarke in 1945, was also achieved soon after.  The first human lunar landing on 20 July 1969 was the next big historic milestone of the Space Age.

Another important day in the history of the Space Age is October 10, 1967, when the Treaty on “Principles Governing the Activities of States in the Exploration and Peaceful Uses of Outer Space, including the Moon and Other Celestial Bodies”, was signed.

World Space Week History

The World Space Week Association (WSWA) began in 1980 as the coordinating agency of “Spaceweek,” a celebration of the first Moon landing, during July 16-24 each year.  It was in 1999 that the United Nations General Assembly declared “World Space Week” to be held every year from 4 to 10 October.   WSWA offered to the UN to serve as global coordinator of World Space Week, and helped organize the first such celebration in 2000.  This has continued since then, expanding both in scope and national participation.

As an international non-government, nonprofit organization, the WSWA is a permanent observer on the UN Committee on the Peaceful Uses of Outer Space. It is supported by voluntary contributions worldwide from numerous sponsors. It is also one of the world’s oldest space advocacy groups.

The largest space event on Earth, the UN-declared World Space Week is essentially an international celebration of the contribution of space science and technology to the betterment of the human condition. World Space Week consists of a myriad of space related events held by space agencies, aerospace companies, schools, planetariums, museums, and astronomy clubs in a common timeframe to achieve greater student participation and public impact.

Every year, WSWA selects a theme to highlight an aspect of space science/technology with broad appeal to humanity. This theme provides guidance to World Space Week participants on the content of their programs. Event holders are encouraged to address the current year’s theme in their events and publicity activities.

The theme for the inaugural year 2000 was “Launching the Space Millenium” as showcased in the poster below. Since then, the practice has continued unbroken.

Nearly 30 nations participated in World Space Week 2000, which was launched at the UN Headquarters on 4 October. Government agencies, industry, schools, science museums, and other institutions in participating nations held a wide variety of space science/technology related events.

UN and Space

In 1999, the UN General Assembly proclaimed World Space Week by resolution 54/68. The main aim is to celebrate the contributions of space science and technology to the betterment of the human condition.

The celebration of World Space Week is under the guidance of the UN Committee on the Peaceful Uses of Outer Space (COPUOS) and the UN Office for Outer Space Affairs (UNOOSA) based in Vienna, Austria.

Today, the UNOOSA is the UN office responsible for promoting international cooperation in the peaceful uses of outer space. It serves as the secretariat for the General Assembly’s only committee dealing exclusively with international cooperation in the peaceful uses of outer space, COPUOS.

The UN has been involved in space activities ever since the beginning of the Space Age, and has been committed to space being used for peaceful purposes only. The UN family strives continuously to utilize the unique benefits of outer space for the betterment of all humankind. Recognizing the common interest of humankind in outer space and seeking to answer questions on how outer space can help benefit the peoples of Earth, the General Assembly adopted its first resolution related to outer space, resolution 1348 (XIII) entitled “Question of the Peaceful Use of Outer Space”.

Space science and technology, and their applications, are increasingly being used to support a wide range of UN activities. They contribute to the work of the UN, including the implementation of recommendations of major world conferences and those of the Third United Nations Conference on the Exploration and Peaceful Uses of Outer Space (UNISPACE III). As a consequence, coordination, cooperation and synergy have become indispensable for those activities to be effectively carried out by the UN system. 

 

Space Week Themes

By way of illustration, the Space Week themes for the years 2001 (Inspiration from Space), 2007 (50 Years in Space), 2011 (50 Years of Human Space Flight), and 2021 (Women in Space) are shown in the posters displayed below:

Here is the complete list of themes included so far:

2022 – Space and Sustainability
2021 – Women in Space
2020 – Satellites Improve Life
2019 – The Moon:  Gateway to the Stars
2018 – Space Unites the World
2017 – Exploring New Worlds In Space
2016 – Remote Sensing – Enabling our Future
2015 – Discovery
2014 – Space: Guiding Your Way
2013 – Exploring Mars – Discovering Earth
2012 – Space for Human Safety and Security
2011 – 50 Years of Human Spaceflight
2010 – Mysteries of the Cosmos
2009 – Space for Education
2008 – Exploring the Universe
2007 – 50 Years in Space
2006 – Space for Saving Lives
2005 – Discovery and Imagination
2004 – Space for Sustainable Development
2003 – Space: Horizon Beyond Earth
2002 – Space and Daily Life
2001 – Inspiration from Space
2000 – Launching the Space Millennium

Space Week Aims

As an international celebration of science and technology and their contribution to the betterment of the human condition, the Space Week aims to:

· Provide unique leverage in space outreach and education

· Educate people around the world about the benefits that they receive from space

· Encourage greater use of space for sustainable economic development

· Demonstrate public support for space programs

· Excite young people about science, technology, engineering, and mathematics

· Foster international cooperation in space outreach and education

· To strengthen the link between space and society through public education, participation, and dialogue on the future of space activity using World Space Week as a focus.

Theme for 2023

As indicated earlier, the theme for the current year is “Space and Entrepreneurship”.  “Our poster for 2023 symbolizes the converging path of space exploration and entrepreneurship,” said Maruska Strah, WSWA Executive Director. “From innovative satellite communication services to promising startups that push the frontiers of space technology, entrepreneurial initiatives are constantly shaping the future of space.”

The two visuals put out by WSWA and reproduced below best describe the concept of Space Entrepreneurship and some indicative opportunities available in the field. These are examined and expanded further in the following section:

Space Entrepreneurship

In the early decades, space exploration was the exclusive preserve of the super powers as a state enterprise.  Private enterprise was confined to the design and development of subsystems required to put together the huge multi-stage launch vehicles and sophisticated satellites and spacecraft needed for space exploration.  With the passage of time, rapid advancements in aerospace technology, coupled with revolutionary developments in related technologies, such as microelectronics, have brought down the costs of development and deployment to such a degree that private enterprise and entrepreneurship became both viable and attractive. For example, the cost of placing a spacecraft in near earth orbit has nosedived from approximately US$ 100,000/kg in 1980 to as low as US$ 1,000/kg today. Part of the reason for this is the ability to place multiple payloads of different sizes and weights in different earth orbits using the same launch vehicle. 

ISRO is one of the forerunners of the multiple launch technique. In Feb 2017, it achieved the incredible milestone of placing as many as 104 different satellites for different customers in different orbits with the same PSLV C37 launch vehicle at highly affordable costs.  This record was bettered recently by Elon Musk’s SpaceX when this private sector company in USA raised the number to 147!   Incidentally, SpaceX has also demonstrated the full potential of reusable rockets.

The dwindling cost of space technology has resulted in a surge of space entrepreneurship worldwide in recent years, as highlighted in this year’s space week theme. The following illustrative graphic focuses on a sample of ten space tech start-ups in different parts of the world this year:

One of these ten startups on focus is Chennai (India) based GalaxEye, started in 2020, which proudly proclaims: “We are building the world’s first multi sensor imaging satellite for earth observation purposes to gather unique insights with our proprietary mission called Drishti to provide intuitive all-time all-weather information over any area of interest across the globe.”

Space Week Activities

The choice of activities open to institutions and individuals as part of the theme for this year is extensive.  Here are a few indicative examples:

·       Promotion of Entrepreneurship

Discussions, seminars, conferences, etc., designed to induce responsive individuals and institutions to take up space science and technology-based entrepreneurship as outlined earlier would serve the primary purpose of this year’s theme.

·       Building model satellite/spacecraft

You can now build your own unique combination of satellites, using free print-it-yourself paper cutout satellite models available online*. Makes for a fun day of real hands-on rocket science and space engineering!

[*For example:

https://spaceplace.nasa.gov/build-a-spacecraft/en/

https://sci.esa.int/web/education/-/35013-cut-out-build]

·      Organizing visits to local or any nearby Science Centre and Space Exhibits

This should be possible in large towns and cities, such as Bangalore. Ask your science centre, museum of natural history, aerospace museum or any other technically oriented Centre for Education for a space related talk or a guided tour through the space exhibits.

·   Inviting rocket clubs to build and launch their own rockets during World Space Week.

Make a contest by getting donors to provide prizes.

·      Organize Spin-offs events.

Discuss spin-offs from space to Earth to educate the public about how space does help in everyday life.

·       Organize Seminars and Conferences

Organize a conference, a summit, symposium or seminar during the week of October 4-10. Invite special guests to speak, invite delegates, arrange a venue, etc. 

·      Organize Lectures

Invite special guests or subject matter specialists to lecture on topics of interest about space Discoveries, what space does for us in everyday life and other topics.

·       Hold Educational Events

Open days in educational and research institutions to have demonstrations and hands on science experiments for students can be very supportive. Have special guests visit the institutions.

·       Invite Industry Experts

Have industry experts go to schools and speak to students about their work in the space industry with demonstrations, experiments and real-world applications of how science and mathematics are necessary.

·       Star Parties

If clear dark night sky opportunities exist it would be an excellent idea to organize star parties with portable telescopes and open them up to the public.

·       Planetarium Shows

At the local planetariums have a party, lecture or event and ask the management to reduce rates or open up to the public for free that week.

Other Examples of World Space Week Events

Here is a long (partial) list of events/programs suggested by WSWA that serve the basic purpose of any World Space Week:

·        Air show with space exhibits

·        Articles about space or Space week in publications

·        Award ceremony for students with best space projects

·        Celebrity, Astronaut, or Cosmonaut appearance

·        Employees give space talks to community organizations

·        Exhibit of space-related art, books or magazines, hardware, maps,  moon rocks or meteorites, photographs, stamps, space memorabilia, or student projects

·        Farmers learning how to use satellite data

·        Festival with space exhibits and activities

·        Films about space

·        Ground testing of space hardware

·        Internet chats with space experts or students in other countries

·        Lectures about space

·        Model rocket launch by students and adults

·        Planetarium with special shows and special events

·        Public meetings to discuss space science/technology spin-offs

·        Press conference introducing space-related product or service

·        Satellite linkage of World Space Week events

·        School activities to excite children about math and science

·        Share your vision for space on your blog* or on this web site

·        Teacher training workshop on space

·        Technical conference and/or industrial exposition on space

·        Telescope viewing of the stars and planets

·        Write letters to newspapers about space

·        Youth “space camp”

[*This blog article is a modest and belated attempt towards this end]

Afterword

The idea for writing this article was inspired by a meeting with Mr A S Abhishek, Founder Secretary of the Gravity Science Foundation, Chamarajanagar, Karnataka, when we discussed how greater awareness could be promoted for this year’s theme of the World Space Week through a radio programme presentation. I am indebted to him for his initiative and for developing such awareness in me.