Hanle’s Dark Sky Reserve: A new window to the universe 

Imagine this: You are in a place where you can stargaze as much as you want. No, we aren’t talking of a planetarium but rather a Dark Sky Reserve. Okay, but what exactly is it? Well, it’s a location of substantial size with an exceptional nocturnal ambience (ideal for starry nights) chosen by the International Dark Sky Association, responsible for tackling light pollution. In Dark Sky Reserve, there are telescopes erected for public stargazing. It is devoid of any kind of light pollution and thus offers telescopes the natural darkness to function properly. Today, there are as many as 195 International Dark Sky Reserves around the world such as Mont Megante Dark Sky Reserve in Canada and the Greater Big Bend International Dark Sky Reserve in the USA. However, the most recent one was built in Ladakh, India. So, if this place was already on your bucket list, there’s now an added reason to visit. Deemed as the first Dark Sky Reserve (spread across 1073 kilometres) in India, it was established on 31st October 2022, in the Hanle region of Ladakh. In fact, it is part of Ladakh’s famous Changthang Wildlife Sanctuary. But what qualified Hanle as a candidate, and how did it become a Dark Sky Reserve? Continue reading to find out! 

Hanle: Ideal home to a Dark Sky Reserve 
A village in Ladakh, Hanle has ideal conditions to access the night sky in its purest form! Firstly, it is a cold desert region with dry weather conditions meaning it is away from human civilisation. This also means that light from distant sources (stars in this case) reaches the observer in its full intensity. Moreover, it has a high altitude of 4500 metres that too on the rain shadow region (perfect for clear skies) of the Himalayas, making it ideal for stargazing. Above all, it has low atmospheric water vapour meaning that light doesn’t easily get absorbed and telescopes can capture all kinds of optical, infrared, sub-millimetre wavelengths of stars in faraway galaxies.  

Keeping these factors in mind, The Indian Astronomical Observatory at Hanle in collaboration with the Indian Institute of Astrophysics and Ladakh Autonomous Hill Development Council (LAHDC) proposed the idea of a Dark Sky Reserve to the International Dark Sky Reserve Association. The Hanle Observatory was already under the Dark Sky Policy that ensures that such observatories are protected from light pollution. And guess what? Lack of light pollution meant an ideal location for a Dark Sky Reserve. This turned it into a tourist attraction, opening livelihood opportunities for locals. Now you know why Hanle is the perfect site to view stars, isn’t it?  

Interestingly, some of India’s prominent indigenous telescopes such as The Himalayan Chandra Telescope (HCT), High Energy Gamma Ray telescope (HAGAR), the Major Atmospheric Cherenkov Experiment Telescope (MACE) and GROWTH-India that were previously part of the Hanle observatory are now located in the Dark Sky Reserve. 

Creating a sanctuary for darkness 
By now you have understood that light pollution can obscure stars in the sky, which is not ideal for stargazing. Maybe that’s why authorities have imposed several restrictions to ensure that Ladakh's Dark Sky Reserve remains suitable for observatories. Artificial lighting inside buildings and on vehicles is strictly prohibited. Extra precautions are also taken for vehicles with high beams approaching the area. Because of the low aerosol content in the air, high beams on vehicles can travel up to 10 kilometres. This can seriously impact observatories. To tackle this issue, delineators have been placed on roads. Special instructions have also been given to all villagers offering homestay to put curtains on their windows to prevent light leakage from homes. If you plan to visit Henle in the hopes of seeing the Milky Way, make sure to follow these rules.