Delhi → Hanle →
Tso Moriri

Premise

The schedule is fixed by one astronomical event: the new moon of 11 September 2026, which occurs at 03:27 UTC (08:57 IST). Lunar illumination stays below one percent across the nights of 10–11 and 11–12 September, so the three nights booked at Hanle (4,500 m) fall on the darkest part of the lunation.

September is also post-monsoon on the Changthang plateau. Precipitable water vapour over the site drops to roughly 2–3 mm in the autumn months, which is the property that makes Hanle usable for optical and infrared astronomy and the reason the Indian Institute of Astrophysics sited its observatory there.

The route ascends through Kashmir and over Zoji La so that altitude gain is gradual, places the core days inside the Changthang dark-sky zone, and adds two nights at Tso Moriri before the return. The drive back covers the whole Manali–Leh highway in one day — Lachulung La, Sarchu, and Baralacha La — rather than breaking it at Jispa.

Why Hanle

• Hanle Dark Sky Reserve — notified in 2022 as India's first, covering 1,073 km² inside the Changthang Wildlife Sanctuary. Reachable on sealed road
• Indian Astronomical Observatory, 4,500 m — run by the Indian Institute of Astrophysics. Instruments include the 2 m Himalayan Chandra Telescope, operated remotely from Hosakote, and MACE, a 21 m gamma-ray Cherenkov telescope commissioned in 2021
• Bortle Class 1–2 — the two darkest categories on the nine-point Bortle scale. At this level the zodiacal light, the zodiacal band, and the gegenschein are naked-eye objects, and the Milky Way casts a diffuse shadow
• Galactic centre still up in the evening — in mid-September the Sagittarius region sets a few hours after dusk. At Hanle's latitude (32.8° N) it culminates near 28° altitude, so September is close to the last usable window before winter
• Changthang plateau — mean elevation about 4,500 m, one of the least densely populated inhabited regions in India. Resident fauna includes kiang (Equus kiang) and Tibetan wolf
• New moon 11 September 2026, 03:27 UTC — matched to the middle night of the Hanle stay

Key figures

Day by day

Observing targets

• Galactic centre — the Sagittarius–Scorpius region sits low in the southwest after dusk, culminating near 28° altitude at this latitude. September is close to the last month it is observable in the evening
• Andromeda Galaxy (M31) — declination +41°, so it passes within about 8° of the zenith at Hanle. Culmination falls roughly an hour after local midnight in mid-September
• Zodiacal light — visible as a cone along the ecliptic before dawn. Requires Bortle 1–3 conditions, which the site meets
• Perseus and Cassiopeia rising through the night, carrying the Double Cluster (NGC 869 / 884) and M31's satellites M32 and M110

Route notes

• Lamayuru, Day 4 — lacustrine clay deposits from a former glacial lake bed, eroded into badland terrain. 11th-century monastery above the village
• Magnetic Hill, near Leh — a gravity-hill illusion. The horizon reference is obscured, so a downhill grade reads as uphill
• More Plains — a high-altitude alluvial basin around 4,600 m, roughly 40 km across and close to level, crossed by the Manali–Leh highway
• Tso Moriri — ringed by peaks above 6,000 m. Korzok monastery sits on the shore; kiang herds are common on the surrounding pasture
• Atal Tunnel — 9.02 km under the Rohtang ridge, the longest highway tunnel above 3,000 m. Connects Lahaul to the Kullu valley year-round
• Manali–Leh highway in one leg — Korzok to Manali crosses Lachulung La (5,059 m) and Baralacha La (4,890 m) on the same day, dropping from 4,522 m at the lake to 2,050 m at Manali. Roughly 400 km and 13–14 hours of driving

Constraints

Vehicle. The loop is entirely on sealed road, with no off-road sections, so a front-wheel-drive Grand Vitara is sufficient. A privately owned white-plate vehicle is required: rented self-drive cars are not issued Inner Line Permits for Ladakh sightseeing.

Altitude. One full rest day in Leh (3,500 m) before continuing to Hanle, giving two nights at intermediate elevation. The profile gains altitude over four days rather than flying into Leh, which keeps the daily ascent within the usual acclimatisation guidance.

The Manali leg. Running Korzok to Manali without an overnight at Jispa makes Day 11 the hardest of the trip: about 400 km, two passes above 4,800 m, and 13–14 hours at the wheel. It needs a pre-dawn start from Korzok. The trade is a second night at the lake, which buys a dawn shoot that the original single-night plan did not allow.

Fuel and water crossings. There is no pump between Karu and Tandi, so the 15 L reserve is carried for the whole Korzok–Manali run. The glacier-fed nalas around Bharatpur and Zingzingbar rise through the day as snowmelt increases, which is the other reason for the early start.

Permits and margin. Inner Line Permit for the Hanle and Tso Moriri sectors, applied for online in advance. Overnight lows near −2 °C at 4,500 m. There is no spare day in the schedule; if Day 11 has to be abandoned, the fallback is to stop at Jispa or Keylong and reach Delhi a day late.