A long-exposure photograph of stars over the Hanle Dark Sky Reserve in Ladakh.
| Photo Credit: Akash Anandh

The temperatures were subzero and freezing. The conditions were unforgiving. We were elated and thrilled being outdoors all night.

At 4,300 metres above sea level, we felt it could have been the Everest Base Camp. In reality, we were at Hanle, in the Union Territory of Ladakh. The air is so thin at such altitudes that the oxygen level is less than 60% of what one is normally used to at sea level. Before getting here, we had to acclimatise ourselves for 48 hours at Leh, at an altitude of 3,500 m, before climbing up to Hanle.

It is definitely not for everyone. But it was certainly for us: we were a group of amateur astronomers invited by the Indian Institute of Astrophysics (IIA) to attend the HDSR Star Party 2023, organised and conducted by IIA.

The Hanle Dark Sky Reserve (HDSR) is India’s first dark sky region, and is centred at Hanle in Eastern Ladakh, around the Indian Astronomical Observatory. HDSR preserves the dark skies by reducing light pollution in the surrounding areas, and uses these dark skies to promote astrotourism as a means to further enhance socio-economic development in the area.

Seeing into dark skies

A dark sky is the night sky as nature meant for it to be: without any light pollution. Light from the human-made objects that we use – especially outdoor lighting sources – blocks our view of the stars and most celestial objects in the night sky.

Ironically, a dark sky lets you see better. From within a light-polluted city, we can typically see only a handful of stars. But from a dark site, we can see thousands in the same location of the sky.

Apart from stars, the Milky Way’s galactic centre and its arms are clearly visible to the naked eye. We can also see several star clusters, nebulae, galaxies such as the Andromeda and the Triangulum.

Zodiacal light – a faint glow of diffuse sunlight scattered by interplanetary dust in the Solar System; airglow – an optical phenomenon caused by faint emission of light in the earth’s atmosphere; and gegenschein – a bright spot in the night sky centred at the antisolar point, caused due to backscatter of sunlight by interplanetary dust – are also visible.

Venus can be so bright in the night sky that its light can cast shadows on the ground, just as moonlight does.

A start to something big

Although some of us astrophotographers were aware of the theories of these optical phenomena and the fact that we could see so many stars and celestial objects under the darkest of skies, it was still an overwhelming feeling to actually observe and experience them under the Bortle Class 1 skies of Hanle.

The Bortle Scale helps amateur astronomers measure the night sky’s brightness at a given location. The scale ranges from Class 1, the darkest skies available over the earth, through to Class 9, which denotes the pale, light-marred skies over the insides of cities.

A sense of thrill as well as caution filled the thin air under the dark skies of Hanle. Observing outdoors in these harsh conditions – with or without equipment – meant one had to be both strong-willed and careful. But it was worth every second as caution soon led to exhilaration and then wonder.

For us amateur astronomers, the three nights and days of the HDSR Star Party made for a great opportunity to observe under pristine night skies. We could also connect with fellow amateur astronomers who had come from various parts of the country: they were experienced amateurs as well as young ones with starlit eyes.

We also got to rub shoulders with professional astronomers, exchanging ideas and information on all things astronomy, including the particulars of visual observation and the techniques of astrophotography, as well as share large telescopes and imaging equipment during the event. In all, it was an unforgettable experience.

Being the first ever dark sky reserve in the country, HDSR is certainly a source of pride for India and will be a blueprint for other dark sites in other regions. And just like at Hanle, upcoming dark sky reserves can also promote astrotourism, which will help both amateur astronomers like us as well as local communities.

The Star Party is also highly likely to evolve into an annual event, and I am glad that I was part of the successful first edition of the HDSR Star Party this year. It was expertly and thoughtfully planned and conducted by Dorje Angchuk, who is the engineer-in-charge at the Indian Astronomical Observatory in Hanle, and Niruj Mohan Ramanujam, head of the IIA SCOPE Section.

I believe the event was a great start to something big for casual stargazers, passionate amateur astronomers, and our space-loving country as a whole.

(Akash Anandh is an amateur astronomer, astrophotographer, writer, and science communicator)

akash.anandh@gmail.com

The Milky Way at night sky in Hanle
| Photo Credit: Akshay Satish

A stunning view of the Milky Way in a 180 degree arc extending from the South to the North at the night sky in Hanle, Ladakh, India’s first dark sky reserve, is an unforgettable memory for a bunch of young students from Coimbatore. “Every inch of the dark sky was filled with stars, star clusters and constellations. It was magical,” recalls Akshay Sathish (18). A team of 11 children led by Obuli Chandran, founder of Mango Education and astronomy educator Mihir Athale are just back from their first expedition to Ladakh where they observed a spectacular view of the night sky at Hanle. “We teach astronomy to students who have a passion for it. Along with theory, we have done several star gazing trips in the South to places like Mudumalai, Hasanur and Udhagamandalam where the skies are clear and there is very less light pollution. This is our first trip with children to the Himalayas,” says Obuli.

Much before it became a dark sky reserve, Hanle was picked by the Indian Institute of Astrophysics to set up an observatory owing to its dry and cold weather. The high-altitude Indian Astronomical Observatory (IAO) located there at 14,764 feet, is one of the highest observatories in the world. “The IAO is a field station of IIA, Bengaluru,” says Dorje Angchuk, chief engineer in-charge at IAO, Hanle. “Our agenda is scientific research for the professional astronomer. Lately, we have been venturing into outreach,” says Dorje adding that every year, students from schools in and around Leh visit the reserve as a part of field trips. Along with his team, he has spent time and effort in orienting the locals to the wonders of astronomy.

The reserve has augmented facilities for night-time astronomy. After sun down, astronomy enthusiasts bring out their cameras and tripods and what follows is star hopping all through the night. “I have been studying astronomy for six years and my fascination with the night sky has increased after the visit to Hanle,” says Rishi Chander (16). For R N Vishnuvardhan (10), the youngest in the team, it was a first-time experience where he could catch a glimpse of the Andromeda Galaxy without using a telescope.

While there, the team also got to experience the nomadic lifestyle and traditions of the people of the region at the Nomadic Festival 2023 at Hanle village in Changthang district. “We could see some of the best of cultural performances, where cultural troupes from different villages in Changthang presented dance, songs and traditional sports. Nomadic communities in Ladakh lead a challenging but self-sufficient lifestyle, adapting to the harsh climatic conditions and high altitudes. They have a deep connection with nature and maintain a strong sense of community and cultural identity,” says Mihir.

The team also got an opportunity to visit the Druk Padma Karpo School in Ladakh that features in the Aamir Khan-starrer 3 Idiots. Besides the night sky, the team also recall breathtaking views of cool blue lakes, snow-capped mountains, and a rejuvenating dip at Chumathang hot spring that bubbles from the ground near the banks of the ice-cold Indus River.

Dorje says they want to use astronomy to promote interest in science among students. “Being a remote observatory, Hanle is a difficult place to visit as it involves lots of travel and students are subject to AMS due to high altitude. Any group coming from the plains needs to be acclimatised for a minimum of two days before they can visit the observatory. We want to build excitement in astronomy with visits to such facilities and also give them an insight on the kind of instrumentation used for the same during day time along with a presentation of the research work carried out there,” he says, adding, “The objective is to make the pristine dark skies, a coveted destination for students.”

The Hanle Dark Sky Reserve is accessible throughout the year. For details on planning a trip from Coimbatore, call 9952243541/ 9894167141.