Is Tonight Good for Stargazing?

Is Tonight Good for Stargazing?

A simple go/no-go for naked-eye nights: score the sky, find the best hours, then dig into the forecast before you drive.

Open Tonight Observing Score · Open Stargazing Weather · Open Dark Sky Window

What “good tonight” actually means

A usable night is not “perfectly clear forever.” It is a stretch of hours with low cloud, acceptable humidity or dew risk, and enough astronomical dark that stars (and maybe the Milky Way) are worth standing outside for. Planets and bright satellites can still work under a brighter Moon; faint structure cannot.

How the Tonight score works (0-100)

Tonight Observing Score compresses cloud, dew/humidity risk, transparency, astronomical dark hours and moonlight into one number, minus a penalty for rain risk, and gives a plain label (how each input is weighted):

• Go (70-100): conditions look solid for a session. Pack and go, then re-check close to departure.
• Maybe (45-69): a usable window is possible, but timing or moisture may limit you. Read the drivers and the hourly outlook.
• Skip (0-44): cloud, dew, moonlight, or lack of dark time make a dedicated trip a poor bet. Stay home or pick another night.

Treat 0-100 as relative guidance for your pin, not a lab measurement. Two sites a short drive apart can score differently when coastal showers or haze sit on one side of town.

Tonight's live score for Georgetown or Lethem, with the chips that make it up, the cloud hour by hour and the week's nights.

The Tonight Observing Score on a dated Georgetown forecast: the dial, the factors behind it and the best clear window.

Best hours tonight

The best time to stargaze tonight is usually:

• After astronomical twilight ends (true dark, not just sunset).
• In the moonless gap, before moonrise or after moonset.
• When the forecast is clearest inside that overlap.

Dark hours only help if the clouds cooperate, so match the moonless window to the clearest forecast stretch. Bright planets can work earlier in twilight. The Milky Way and faint structure need true dark plus darker skies.

Midnight is not always best: a bright Moon or a cloud bank at midnight can make 21:00 or 03:00 better. If dark hours and clear hours barely overlap, take the overlapping hour. A short clear dark window beats a long cloudy one.

Tonight on one strip: twilight, the Moon, the moonless dark window and the forecast cloud for each hour.

The forecast is clear all night and the Moon rises at 23:00. When is the best dark stretch?

• Right after sunset
• From the end of astronomical twilight until moonrise (the right answer)
• After moonrise, when the Moon lights the way
• Only at midnight

True dark starts when astronomical twilight ends, about 70 minutes after sunset in Georgetown, and the moonless gap lasts until the Moon rises.

FAQ: Is tonight clear enough?

Cloud is low but the score says Maybe: why? Dew risk, poor transparency, a bright Moon, or a short dark window can hold the label down even when the sky looks “clear” on a casual forecast.

Cloud is low but the score says Maybe. What could be holding it down?

• Nothing: Maybe always means cloud
• Dew risk, haze, a bright Moon or a short dark window (the right answer)
• The light pollution at your pin
• The date of the next new Moon

The score also weighs dew, transparency, darkness and the Moon, so a clear sky can still score Maybe.

Can I still see planets on a Skip night? Sometimes. Bright planets and the Moon punch through haze and partial cloud. Skip usually means “do not drive far for faint stars,” not “the sky is empty.”

Does a full Moon ruin everything? It washes out the Milky Way and faint Milky Way dust. It does not cancel Moon-aware targets, bright constellations, or many ISS passes. The score already takes up to 15 points off for a bright Moon that is up all night; Sun/Moon Dark Window gives the exact moonless hours.

City light vs weather: which matters more tonight? Weather decides whether you see anything. Light pollution decides how deep you see. Score first for go/no-go; then improve the site with Dark Sky Finder when the forecast cooperates.

When Guyana (and other humid tropics) prove the rule

Near the equator and on humid coasts, afternoon convection and overnight dew can flip a “clear” evening into a fogged lens or a sudden shower line. Georgetown and the coast often clear after rain while an inland pin stays socked in, or the reverse. Set the score to the place you will stand, not only your home address, and open Stargazing Weather for the hourly detail behind the label.

Timing works differently here too. Near the equator night length barely changes through the year (about 11.5 to 12.3 hours at Georgetown), and twilight is short: astronomical darkness starts about 70 to 77 minutes after sunset, between about 18:45 in early November and 19:30 in early July at Georgetown. Dew often rises after midnight, so prefer the early dark stretch when humidity climbs late.

Step-by-step decision

1. Open Tonight Observing Score and set location.
2. Read Go / Maybe / Skip and the 0-100 score. If the label is Skip, pick another night from the 7-night outlook instead of forcing a drive.
3. If Maybe or Go, open Stargazing Weather for cloud and humidity by hour.
4. Open Dark Sky Window for the Moon and twilight: note when astronomical night starts and the longest moonless gap, then keep the hours that overlap the clearest forecast.
5. If the sky is usable but washed out by city glow, pick a darker pin with Dark Sky Finder.

Common mistakes

• Trusting a national headline (“clear”) instead of the site pin and Tonight score.
• Planning only by sunset, not astronomical twilight.
• Driving on a Go night into a bright Moon without checking moonrise in Dark Sky Window.
• Using home-city weather while observing from a darker inland site.

Next

• How-to: How to Use Tonight Observing Score
• Topic: How Tonight Score Is Weighted
• Topic: Time-of-Day Observing Guide
• Related: First Telescope Night
• Tools: Tonight Score, Stargazing Weather, Dark Sky Window