Observing Skills · 5 of 12
Binoculars First
Why is a pair of binoculars a better first instrument than a telescope?
You do not need a telescope to start. What 10×50 means, why light beats magnification, and the Pleiades, the Orion Nebula, Jupiter's moons and the Moon's terminator in a pair.
You’ll be able to read the numbers on a pair of binoculars, and find a cluster, a nebula, Jupiter’s moons and craters with them.
Where and which night
Working out when this is best placed from where you are…
Where
Kept for this guide only, until you change it here — your map settings, and every other guide, stay as they are.
Print, play outside or present
Scan with a phone's camera, or open
Sources
- Kelly, "Choosing Binoculars for Astronomy", RASC Halifax Centre (2021) — the two numbers, light grasp, exit pupil, 6–7° fields and the limit of a steady hand
- Kelly (RASC, 2021) — "many astronomical objects are hard to see not because they are small and need more magnification, but because they are faint and need more aperture"
- Kelly (RASC, 2021) — "magnifications higher than 10 are tough to hold steadily and lead to narrow fields of view"
- Dyer, "Buying Binoculars for Astronomy", Sky & Telescope — divide the aperture by the magnification: a 7×50's exit pupil is 7.1 mm, and pupils shrink with age
- NASA JPL, What's Up: October 2011 — "Jupiter's four Galilean moons can be spotted with a pair of steady binoculars"
- NASA Science: Jupiter Moons — the four largest were first observed by Galileo Galilei in 1610
- Astronomy, "10 tips for observing the Moon" — near first quarter the shadows are longer and features stand out in sharp relief; the full Moon is the worst time
- Meeus, Astronomical Algorithms, 2nd ed. (1998), ch. 44 — the positions of Jupiter's four big moons
With a keyboard, focus the sky, aim it with the up and down arrow keys, and press Enter to drop the pin at the centre of the view; or press Show me.