Why is the lunar surface temperature so extreme?

The Moon has no atmosphere to distribute or retain heat. In direct sunlight, temperatures reach +127 °C (400 K) at the sub-solar point; on the nightside they fall to −173 °C (100 K) — a 300 °C swing driven purely by the presence or absence of solar radiation. MoonSync estimates temperature using the Stefan–Boltzmann model: T (K) = 400 · sin(altitude)^0.25.

How accurate are MoonSync's calculations?

MoonSync uses simplified Keplerian orbital elements and geometric optics suitable for education and illustration — not for navigation. Earth–Moon distance accuracy is ±3,000 km; LTC offset uses NASA's 2023 value of +56.0205 µs/day; phase timing drifts ≈±30 min over a synodic month. For navigation-grade results, consult JPL Horizons or USNO data.

MoonSync

MoonSync — Lunar Clock & Site Selector

Lunar Coordinated Time, selenographic site selector & Moon resident pass

Showing example data: Apollo 11 — Tranquility Base. Click the map or choose a preset to view your site.

Lunar Time (LTC)

Moon Coordinated Time

2026-05-06 01:08:55.922 LTC

Earth UTC

2026-05-06 01:08:55.383 UTC

Accumulated drift since page load

+0.000000 μs ahead of Earth

Lunar Calendar

Moon PhaseWaning Gibbous

Days since new moon18.69 / 29.53

Cycle Progress63.3%

🌑 New🌕 Full🌑 New

Lunar Site Map

Lat: +0.7° Lon: +23.5°

Click anywhere on the map to select a lunar site

Preset Sites

Illumination Status

Lighting State

Lunar Day

Until next sunset

5d 9h

Solar Position

Altitude

+65.6°

Azimuth

91.5°

Earth–Moon Distance

403,865kmLIVE

Earth Phase (from Moon)

Earth illumination

16.5%

Earth's illuminated fraction as seen from this lunar site.

Phase

Waxing Crescent Earth

Environmental Insights

Surface Temperature Estimate

117.6°C

Based on Stefan-Boltzmann solar angle model. Range: −173°C to +127°C.

Solar Panel Output

Panel area (m²):

1239 W

Solar constant: 1,361 W/m²

Shadow Length (1 m object)

0.45 m

Moon Resident Pass

Coordinates

0.67°N, 23.47°E

LTC Timestamp

2026-05-06 01:08:55.922 LTC

Lighting

☀ Lunar Day

Surface Temp.

117.6°C

Badge

⚑ Lunar Archaeologist

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Lunar Archaeologist

Solar Position & Twilight Calculator — Solar InsightCalculate solar altitude, azimuth, golden hour, and civil/nautical/astronomical twilight for any location on Earth.fastool.io Sidereal Time Calculator for AstronomersConvert between local sidereal time and UTC for telescope alignment and observation planning.fastool.io

How MoonSync Works

What Is Lunar Coordinated Time (LTC)?

LTC is a proposed Moon-based time standard. NASA's 2023 analysis found that Moon clocks gain +56.02 µs per Earth day: weaker lunar gravity causes a gravitational blueshift that outweighs the transverse Doppler redshift from lower orbital velocity. MoonSync accumulates this offset from J2000.0 (Jan 1, 2000 12:00 UTC).

NASA — What Time Is It on the Moon?

How Is Lunar Illumination Determined?

The sub-solar point (the Moon's 'noon' longitude) moves 360° per synodic month (29.53 days). Solar altitude at any surface coordinate is computed via the spherical law of cosines. Above 0°: lunar day; below 0°: lunar night. Polar sites (|lat| ≥ 87°) can see permanent sunlight (illuminated peaks) or permanent shadow (PSR craters).

USNO — Moon Illumination Data

What Is a Permanent Shadow Region (PSR)?

PSRs are craters near the lunar poles never exposed to direct sunlight, due to the Moon's low axial tilt (1.54°). Temperatures hover around −230 °C, cold enough to trap water ice for billions of years. NASA's LCROSS mission (2009) confirmed water ice deposits in Cabeus crater near the south pole, making PSRs prime candidates for future lunar bases.

NASA Science — Permanently Shadowed Craters

How Is Earth–Moon Distance Calculated?

MoonSync uses a first-order Keplerian ellipse: r = a(1 − e·cos M), where a = 384,399 km (semi-major axis), e = 0.0549 (eccentricity), and M is the mean anomaly from perigee. Accuracy is ±3,000 km. For navigation-grade ephemerides, NASA/JPL's Horizons system integrates the full DE440 planetary solution.

JPL Horizons — Lunar Ephemeris

Frequently Asked Questions

What is Lunar Coordinated Time (LTC)?: LTC is a proposed Moon-based time standard. Because lunar gravity is weaker (gravitational blueshift) and the Moon's orbital speed is lower (transverse Doppler redshift), Moon clocks run approximately +56.02 µs faster per Earth day than Earth clocks. MoonSync cumulates this offset from J2000.0 (Jan 1, 2000, 12:00 UTC) to display the total LTC lead over UTC at any moment.
Why is the lunar surface temperature so extreme?: The Moon has no atmosphere to distribute or retain heat. In direct sunlight, temperatures reach +127 °C (400 K) at the sub-solar point; on the nightside they fall to −173 °C (100 K) — a 300 °C swing driven purely by the presence or absence of solar radiation. MoonSync estimates temperature using the Stefan–Boltzmann model: T (K) = 400 · sin(altitude)^0.25.
What is a Permanent Shadow Region (PSR)?: PSRs are polar craters on the Moon that have never received direct sunlight, due to the Moon's low axial tilt (1.54°). Temperatures can fall to −230 °C — cold enough to preserve water ice for billions of years. NASA's LCROSS mission (2009) confirmed water ice at the lunar south pole. MoonSync classifies any polar site (|lat| ≥ 87°) with negative solar altitude as a PSR.
How accurate are MoonSync's calculations?: MoonSync uses simplified Keplerian orbital elements and geometric optics suitable for education and illustration — not for navigation. Earth–Moon distance accuracy is ±3,000 km; LTC offset uses NASA's 2023 value of +56.0205 µs/day; phase timing drifts ≈±30 min over a synodic month. For navigation-grade results, consult JPL Horizons or USNO data.

Real-time lunar clock (LTC), selenographic site selector & environment data. Free, browser-only, no sign-up. · LTC offset: NASA 2023 (+56.0205 µs/day) · Orbit: simplified Keplerian DE elements · Temperature: Stefan–Boltzmann model · All 14 calculations execute client-side — zero network requests, zero data transmitted.