L6 Tycho Crater
An 85 km complex crater in the Southern Highlands — one of the youngest and most violent formations on the Moon, with a 1.6 km central peak and rays that streak across the entire lunar surface.
If there is one crater every person on Earth has seen, it is Tycho. Even without a telescope, Tycho appears as a brilliant bright spot on the southern lunar limb during a Full Moon. But through binoculars or a telescope, it transforms from a simple white dot into one of the most violent and spectacular geological formations in the solar system.
Designated as Item L6 on the Lunar 100 list, Tycho is often the first “serious” target for beginner astronomers, yet it offers enough complexity to keep experts coming back for a lifetime.
L6 Tycho
Southern Highlands · Complex Crater📉 Vital Statistics
🔭 Field Notes
Tycho is the “splash crater” of the southern highlands — extremely young by lunar standards, which is exactly why its ray system still burns so bright: the solar wind hasn’t had time to darken the ejecta blanket the way it has on older, duller craters. Tycho changes personality entirely depending on when you look. At Full Moon it flattens into a brilliant white starburst with almost no visible depth, its rays washing out any hint of structure underneath. Around Moon Day 9, with the terminator nearby, that same crater becomes a study in shadow — the central peak throws a long, sharp line across the floor and the terraced inner walls snap into relief.
- ▶ Central Peak: A massive peak rising 1.6km (1 mile) from the floor. Look for its shadow at sunrise — its length is the giveaway that you’re catching Tycho at the right time.
- ▶ Dark Halo: During a Full Moon, look for the dark ring of impact melt immediately surrounding the bright rim — visible precisely because the rays around it are so overexposed.
- ▶ The Ray System: Some rays stretch over 1,500 km, reaching all the way to Mare Serenitatis. Trace a single ray across the disk if you can — it’s a genuine challenge even in decent binoculars.
📍 Nearby L100 Targets
🚀 Mission Log
Target Acquisition
Follow the Rays
Tycho is the prominent “Navel of the Moon” in the south. Even with binoculars, look for the massive system of bright white rays radiating outward across the entire lunar surface. Follow them back to their origin point in the Southern Highlands.
Identify the Neighbors
To confirm you have the right crater, look directly South for the massive, ancient crater Clavius (L9). Contrast this with Tycho, which is smaller (85km), much sharper, and visibly deeper.
The Peak Challenge
Increase your magnification to 150x+. Look for the massive central peak rising 1.6km (1 mile) from the floor. At sunrise (Day 8-9), this peak casts a dramatic, spire-like shadow across the crater floor.
📝 Observation Log: Tycho
0/3 CompleteIs Tycho visible tonight?
Check our real-time tool to see if the Moon is in the Waxing Gibbous or Last Quarter phase.
Check Moon Phase TodayReturn to the List
Ready to find the next target? Go back to the full map to see what else is visible tonight.
← Back to Lunar 100 Map
When to Observe Tycho
Timing is everything. While Tycho is the star of the Full Moon due to its massive ray system, the Full Moon is actually the worst time to see the crater's structure. To see the depth, the terraced walls, and the central peak, you need shadows.
- Best Viewing: 9 days after New Moon (Waxing Gibbous) or 22 days after New Moon (Last Quarter).
- Sun Angle: Look when the Terminator (the day/night line) is nearby. The low sun angle will cast the central peak’s shadow across the crater floor, creating a dramatic 3D effect.
What to Look For
Tycho is a "Complex Crater," meaning it was formed by such a massive impact that the lunar crust rebounded, creating a mountain in the center.
1. The Ray System
Tycho is young—only about 108 million years old. Because it is so fresh, its "ejecta" (the material thrown out during impact) hasn't darkened yet. These rays stretch over 1,500 kilometers, reaching as far as the Mare Serenitatis.
- Challenge: Can you trace a single ray all the way across the lunar disk?
2. The Central Peak
Rising 1.6 kilometers (1 mile) from the crater floor is a jagged mountain peak. This is not a volcano; it is bedrock that splashed upward like a water drop hitting a pond, then froze in stone.
- Challenge: Under high magnification, try to spot the "secondary peak" just next to the main one.
3. The Dark Halo
Surrounding the bright white crater rim is a subtle, darker ring. This is impact melt—rock that was instantly vaporized and melted into glass during the collision, darkening the immediate area.
The Science: The Dinosaur Connection
Tycho is a newcomer to the Moon. Analysis from the Surveyor 7 probe (which landed on Tycho's rim in 1968) confirms the crater is roughly 108 million years old. This means Tycho was formed during the Cretaceous period on Earth.
It is likely that a dinosaur looked up at the moon one night and saw a flash of light, witnessing the birth of the scar we study today.