Night Glass
How to use Night Glass
Night Glass tells you what the sky is offering tonight from your place. It looks at the Milky Way, meteor showers, planets and bright satellites. It sits beside Sky Contours, which shows how the moon washes the sky, and Transparency, which shows how clear the air is.
Getting started
- Choose your place. Type a name, tap the target button to use your location, or choose on a map.
- Read the night card at the top. It gives tonight's score and the one thing most worth looking at.
- Scroll for the detail: what is on this week, what is coming up, the planets, the season's sights, and bright passes. The Sky Contours link sits under those. Showers are on the night card.
- Tap a line in What is on, Coming up, or Season's sights. The Sky Contours link then opens on that moment. Tap Open in Transparency on the night card to check the air.
Reading the numbers
The night score
The night score runs from 0 to 100. It is how much the sky has to offer tonight. Higher means a richer night. It weighs the Milky Way, then the showers, then the planets. When Transparency rates the air Fair or Poor, the score is lowered in step with that. The number is shown in copper. The moon does not change it.
Score bands
- Worth staying. 75 to 100.
- A rich night. 60 to 74.
- Something up. 40 to 59.
- A thin night. Under 40.
Moon, in per cent
How much of the moon is lit. Under 25%, and with the moon up, the notes call it a dark moon. From 40% the night card says it is enough to soften a dark sky. At 75% and above, the night card says this is not a dark sky night, and fainter seasonal sights can be marked washed out by the moon when the moon is up.
Degrees
How high something is above the horizon. 0° is the horizon and 90° is straight overhead. At arm's length, your fist is about 10°.
Magnitude
How bright something is. Lower is brighter, and negative numbers are the brightest of all. Venus at −4.2 is dazzling, Jupiter at −2.0 is brilliant, and Uranus at 5.6 is right at the limit of the eye, so it needs a glass.
Shower numbers
The number beside a meteor shower is how many meteors an hour you could see under a perfect dark sky, with the radiant overhead. That is the zenithal hourly rate. Under a bright moon or in town, expect far fewer.
Times
All times are 24-hour and local to your chosen place.
Viewing tags
- Naked eye. Nothing needed.
- Binoculars. A small pair helps a lot.
- Telescope. Needs a telescope.
Good to know
“Hazy then” means Transparency expects haze, and that hour is Fair or Poor. Cloud, rain and the other causes get their own short line in the same place.
Night Glass tells you what is up there. Sky Contours shows where the moon spoils it.