Guides

What helps when you start looking at the night sky, and how to get the most out of the NowSky simulators. Each guide ends with views you can open in the simulator.

Using the simulators

How to use the sky view, orbit view and 3D star map, and what each one shows.

• 🔭How do you read tonight's sky with the NowSky Sky view?A walkthrough of the Sky view: set your place and time, tap objects for details, run time forward or back, use the compass, search, and the chips.
• 🪐How do you travel through time in the solar system with Orbit view?How to use Orbit view: follow a planet, zoom and tilt, play or rewind time, open moon systems, trace probes and replay eclipses and milestones.
• 🌌How do you see real distances to the stars with the 3D star map?See nearby stars at true distances in the interstellar 3D map: rotate, use the ruler, read star cards, measure distances and share a view by its address.

Observing basics

Watching the night sky without a telescope — choosing a place and time, finding north, telling planets from stars.

• 🔭How do you start stargazing with just your eyes?Dark adaptation, red lights, light pollution and the Bortle scale, moonlight and weather: the basics to know before a first night of naked-eye stargazing.
• 🧭How do you find Polaris and true north in the night sky?Use the Big Dipper or Cassiopeia to find Polaris, learn why its altitude equals your latitude, and how the Southern Cross points south below the equator.
• 🌓Why does the Moon change phase, and when is it best to observe?Why the Moon waxes and wanes over 29.5 days, when each phase rises and sets, and how to plan Moon watching and dark-sky nights around it.
• 🪐Is that bright point a planet or a star? How to tell them apartSteady light, a place on the ecliptic, slow drift, brightness and colour: how to tell planets from stars, with tips for Venus, Jupiter, Mars and Saturn.
• ✨Which constellations can you see each season, and why do they change?Why the evening sky changes through the year, plus the key star patterns of each season for both hemispheres, from Orion and the Summer Triangle to Crux.

Terms and concepts

Coordinates, brightness, distance and eclipses — the ideas that come up in every astronomy article, in plain words.

• ✨How does the magnitude scale measure star brightness?Smaller magnitudes mean brighter stars, and each step is about 2.5 times. The naked-eye limit, absolute magnitude and familiar examples.
• 📏How far are an AU, a light-year and a parsec?An AU is about 150 million km, a light-year 9.46 trillion km, a parsec 3.26 light-years. Light travel time makes these scales easier to grasp.
• 🧭How are sky positions given? Altitude, azimuth, RA and declinationAltitude and azimuth say where to look from where you stand; RA and Dec fix a star on the sky. How both work, and how to measure angles by hand.
• 🌒Why don't solar and lunar eclipses happen every month?The Moon's orbit is tilted about 5°, so eclipses happen only in two eclipse seasons a year. Types of eclipse, the red Moon and the saros cycle.