Lost River Caverns is a cave in Northampton County, Pennsylvania. The nearest town is Hellertown, about 800 m away (Lost River Caverns lies E of town).
Lost River Caverns is a natural limestone cavern located on the east side of Hellertown, Pennsylvania, United States, and consisting of five chambers. The caverns were formed by the karstification or dissolving of the limestone by water. In the past the caverns have been called Rentzheimer's Cave and Lost Cave. The "Lost River", so named because the source and mouth of the river have not yet been discovered, flows through it. The temperature in the cave is consistently close to 52 °F (11 °C). There is a gift shop and a museum before the entrance. It was discovered in 1883 when a limestone quarry cut into it. It is open to the public.From the Wikipedia article “Lost River Caverns”, licensed under CC BY-SA 4.0.
Sunrise & sunset directions
At Lost River Caverns the sunrise point swings a long way through the year: about 58° (ENE) at the June solstice and 121° (ESE) in late December. Sunset moves from 303° (WNW) in June to 239° (WSW) in December, and the midday sun climbs to 73° in summer but only 26° in winter.
| Date | Sunrise | Azimuth | Sunset | Azimuth | Noon sun | Daylight |
|---|---|---|---|---|---|---|
| March equinox (Mar 20) | 7:06 AM | 90° E | 7:14 PM | 271° W | 49° | 12h 08m |
| June solstice (Jun 21) | 5:31 AM | 58° ENE | 8:36 PM | 303° WNW | 73° | 15h 05m |
| September equinox (Sep 22) | 6:49 AM | 89° E | 7:00 PM | 271° W | 50° | 12h 11m |
| December solstice (Dec 21) | 7:22 AM | 121° ESE | 4:38 PM | 239° WSW | 26° | 9h 16m |
Azimuth is measured clockwise from true north (90° = east, 270° = west). Computed for 2026; values change by less than a degree from year to year.
Golden hour & blue hour by month
Caves are lit artificially — show caves have fixed lighting, so a fast lens and high ISO beat flash, which flattens formations.
| Month (15th) | Blue hour starts | Sunrise | Golden hour ends | Golden hour starts | Sunset | Blue hour ends | Daylight |
|---|---|---|---|---|---|---|---|
| January | 6:54 AM | 7:24 AM | 8:06 AM | 4:17 PM | 4:59 PM | 5:29 PM | 9h 35m |
| February | 6:28 AM | 6:56 AM | 7:34 AM | 4:58 PM | 5:37 PM | 6:05 PM | 10h 40m |
| March | 6:47 AM | 7:14 AM | 7:50 AM | 6:32 PM | 7:08 PM | 7:35 PM | 11h 54m |
| April | 5:55 AM | 6:23 AM | 7:00 AM | 7:04 PM | 7:40 PM | 8:09 PM | 13h 17m |
| May | 5:15 AM | 5:46 AM | 6:25 AM | 7:32 PM | 8:12 PM | 8:43 PM | 14h 26m |
| June | 4:58 AM | 5:31 AM | 6:12 AM | 7:53 PM | 8:34 PM | 9:08 PM | 15h 04m |
| July | 5:12 AM | 5:44 AM | 6:24 AM | 7:52 PM | 8:32 PM | 9:04 PM | 14h 48m |
| August | 5:43 AM | 6:13 AM | 6:50 AM | 7:23 PM | 8:01 PM | 8:30 PM | 13h 48m |
| September | 6:15 AM | 6:43 AM | 7:19 AM | 6:36 PM | 7:12 PM | 7:40 PM | 12h 29m |
| October | 6:45 AM | 7:13 AM | 7:50 AM | 5:46 PM | 6:23 PM | 6:50 PM | 11h 10m |
| November | 6:19 AM | 6:49 AM | 7:29 AM | 4:05 PM | 4:45 PM | 5:14 PM | 9h 56m |
| December | 6:48 AM | 7:19 AM | 8:02 AM | 3:52 PM | 4:36 PM | 5:07 PM | 9h 17m |
Local time (America/New York), including daylight saving time. Golden hour runs from about −4° to +6° solar altitude, so the morning golden hour begins during blue hour, before sunrise.
Milky Way & night sky
From Lost River Caverns, the Milky Way core is visible in a dark sky from March through September. June gives the longest window (about 4.7 hours on a moonless night), and the core peaks around 21° above the southern horizon. Our light-pollution model puts the sky at about Bortle 6 (bright suburban sky), so expect visible sky glow; drive away from towns for better results.
| Month | Core visible (15th) | Hours | Max altitude | Direction |
|---|---|---|---|---|
| January | Below 10° in darkness | — | -2° | — |
| February | 5:18 AM – 5:18 AM | 0.0 | 11° | SE → SE |
| March | 4:29 AM – 5:39 AM | 1.2 | 17° | SE → SSE |
| April | 2:28 AM – 4:38 AM | 2.2 | 20° | SE → S |
| May | 12:23 AM – 3:43 AM | 3.3 | 21° | SE → S |
| June | 10:39 PM – 3:19 AM | 4.7 | 21° | SSE → SSW |
| July | 10:30 PM – 2:00 AM | 3.5 | 21° | S → SW |
| August | 9:43 PM – 11:53 PM | 2.2 | 20° | S → SW |
| September | 8:45 PM – 9:55 PM | 1.2 | 17° | SSW → SW |
| October | 7:53 PM – 7:53 PM | 0.0 | 11° | SW → SW |
| November | Below 10° in darkness | — | -1° | — |
| December | Below 10° in darkness | — | -19° | — |
Window when the galactic core is at least 10° high during astronomical darkness on the 15th of each month. Pick nights within a few days of the new moon. Plan exact nights with the Milky Way planner.
Estimated sky darkness: 6 Bortle 6 — Bright suburban sky. The Milky Way is only visible near the zenith; the sky glows grey-orange in photos. Modeled zenith brightness ≈ 18.99 mag/arcsec². Aurora needs roughly Kp 6.5+ to show low on the northern horizon here.
Weather & best season
Long-term NASA satellite data for this area show September as the clearest month (about 52% average cloud cover) and December as the cloudiest (68%). July is the warmest month and January the coldest, which matters for gear, snow access and how long batteries last at night.
Average cloud cover (%)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| High °F | 65 | 73 | 76 | 90 | 89 | 95 | 104 | 101 | 97 | 94 | 78 | 71 |
| Low °F | -7 | -11 | -8 | 21 | 28 | 41 | 49 | 50 | 38 | 24 | 10 | -3 |
| Precip. (in) | 2.9 | 3.1 | 3.5 | 3.8 | 3.9 | 4.9 | 4.9 | 4.5 | 4.8 | 4.4 | 3.5 | 3.9 |
Monthly climatology for the surrounding 1° grid cell from NASA POWER (MERRA-2). Mountain sites can be colder and cloudier than the cell average.
Photography tips for this cave
- Never touch formations — skin oils stop their growth.
- Follow White-nose Syndrome decontamination rules where posted to protect bats.
- Many show caves restrict tripods on tours; ask in advance or bring a small beanbag.
- Use manual focus with focus peaking in low light.
- Tell someone where you're going in remote areas and carry the ten essentials.
Season: Cave interiors stay at a constant temperature year-round; summer tours fill up, so book ahead.
Suggested gear: Fast lens (f/1.8–f/2.8), High-ISO camera, Small beanbag. Work out exposures with the depth of field, ND filter and NPF rule calculators.
Nearby photo spots
Other locations within 25 km of Lost River Caverns, closest first.
Covered Bridge
Covered Bridge
Covered Bridge
Covered Bridge
State Park
Covered Bridge
Covered Bridge
Covered Bridge
State ParkFAQ
When is the best time to photograph Lost River Caverns?
What time is golden hour at Lost River Caverns?
Where does the sun rise and set at Lost River Caverns?
Can you see the Milky Way from Lost River Caverns?
Do you need a permit to photograph at Lost River Caverns?
How far is Lost River Caverns from Hellertown?
Sources
Location data: Wikidata, Wikipedia. Sun, moon and Milky Way times are computed by LWPhoto Atlas for 2026. Climate: NASA POWER. Sky darkness is a population-based estimate (Walker's law), not a measurement. See data sources & licenses.