Sidewalk Astronomy Tips

What is a Sidewalk Session?

A Sidewalk Astronomy Session is the same as a Star Party but not at a dark site. The same guidelines and etiquette apply. The major differences are the level of light pollution, and that the visitors usually didn’t plan on attending. Some people don’t know what to make of us and figure we must be selling something. Often the more adventurous folks are the young ones who ask us “what the heck are we doing”. The ones that stop to look through our scopes often stop and chat. Often kids will drag their folks over to see. If people don’t say “Oh Wow!” when they look through the eyepiece, we know we need to adjust our scopes. Sometimes we politely invite / encourage the passers-by who look curious to stop and have a look. Lots of interesting discussions arise. We really enjoy chatting with people about anything to do with astronomy. Sometimes, people will rush home and drag their family members back to look though our scopes. We find the enthusiasm infectious.

  • See our Star Party Etiquette page to get an idea of what to do. In general, the same guidelines apply about touching equipment, but there is no need to dark-adapt or worry about flashlights.. Then come back here to get an idea of what you will see from the sidewalk.
  • Check this to get an idea about the origins of sidewalk astronomy.
  • Richard’s nice  article on how sidewalk fits into astronomy public outreach.

When do OAFs Hold Sidewalk sessions

We’re limited by the weather, so it’s hard to predict. Check our Current events listing or our Twitter Feed to see if we’ve scheduled a date. in general, we like to hold sidewalk sessions when you can see the moon in the west in the evening.

What you can see from the sidewalk

Sidewalk astronomy sessions are held in places most convenient to the public, especially high foot traffic areas like malls or movie theaters. The light pollution will be very significant, sometimes you have to look hard just to find more than a handful of stars. But some objects can be seen and seen quite clearly. We hold our sessions in front of the Chapters in the Centrum in Kanata. Please have a look at our General Observing Tips page to help you get the most out of what you can see.

We hope to see you there!

The Moon

To someone who has never seen the moon though a scope, it sounds like a boring object. Everyone’s seen it with their own eyes. But seeing the wealth of impact craters, ejecta blankets, rays, mountains, rilles, and lava flows in a telescope is a dramatic experience.

Generally it is the moon that drives our sidewalk astronomy session schedule. We try to get out somewhere between the first and last quarter phases of the moon, but not the full moon. Why? Because at this time the sun’s light is at an angle to the moon and the craters and other features cast shadows and can be easily picked out and you really get an idea of the rough topography of the moon and a feel for the depth of some of the craters. During a full moon the light from the sun is straight on, there are virtually no shadows and the moon looks like a big smooth marble with no relief at all.

We always see the same side of the moon. It seems to never rotate. It does wobble some though, so we can see about 59% of the surface from earth over the course of a year. The reason is that the moon rotates once for each trip around the earth (so it points the same face toward us), but the orbit is elliptical and so the moon’s rotation and it’s revolution are not perfectly synched (so we see it wobble a bit).



The undisputed showpiece of the night sky. No one ever gets tired of looking at Saturn and its rings for the shear beauty of the planet. “Seeing Saturn for the first time” is the most popular story amateur astronomers tell about how they got hooked on astronomy. Often several of Saturn’s moons are visible too. The rings wobble with respect to earth over a 15 year period. Some years they are virtually edge on so it is hard to see, other years they are spread out wide and magnificent.

When Galileo was studying Saturn, they went edge on and he thought that the rings had somehow vanished so he gave up studying the planet for a while. Telescopes are a bit better these days, he would drool.



This is the king of planets, it is the largest. Like Saturn one never tires of Jupiter. It is famous for its Great Red Spot, and its almost always visible four major moons, the Jovian moons. On good nights many astronomers love to study the bands and colourful festoons on the planet’s surface, and the Jovian moons are always moving. Many people enjoy watching the Jupiter’s moons transit across the face of the planet and watch the shadow they cast on the surface as the do so. Jupiter is never boring, there is always something different to see every time you look at it. If you watch very carefully you can seen subtle changes in 20 minutes on the planet’s surface and see the moons changing position.

The Great Red Spot is actually a huge and rather nasty storm (huge as in as in bigger than the planet earth) that has been raging since at least the 17th century.

Galileo‘s first observation of moons going around Jupiter may be the most politically controversial in history: it meant there were no crystal spheres which where part of the dogma of cosmology and religion at the time.



Enigmatic Mars is our close neighbour, and sometimes it is the closest (but usually Venus is closer). It is less enigmatic now that we have had exploratory vehicles on the surface of course, but for centuries it has driven astronomers nuts (and still does). While close, it is small and bright so usually it is hard to see features. The best time to view Mars is every 26 months or so when it makes its closest approach to earth. Many astronomers prepare in advance for those events. Normally you can make out the polar ice caps and glean some hint as to surface features. On exceptional nights those features are quite visible and rewarding to see.

The highest know mountain in the solar system is on Mars. It is Olympus Mons, a volcano actually, it easily dwarfs Mount Everest here on Earth.



Or the Sun as most people probably call it, is the star that the earth and the rest of the solar system orbits. During the day many astronomers are fascinated with observing the Sun. Solar eclipses have inspired and awed people throughout history. Many people forget about the Sun, but it is fascinating and beautiful to view. Visual observation of the Sun is a unique experience in astronomy in that you can see it change before your eyes (slowly, like watching clouds change shape).

With different equipment you can look into different (deeper) layers of the Sun. Sunspots and solar flares have an organic beauty that is compelling. Everyone remembers their first closeup views of Sol.

But remember all of the warnings about viewing the Sun are very serious! Never use any kind of optical device to look at the Sun unless it is made specifically for that purpose, make sure your scope is never pointed at the Sun without your solar filter in place, and make sure a passer-by can’t simply pull it off (it’s happened 🙁 ). Ever burn things with a magnifying glass and the Sun? That is why! Your blink reflex will not be fast enough to protect you. But under supervision and with the right equipment it is a completely safe and must-see experience.

When Galileo was examining the Sun, he used a candle to blacken his eyepieces and the objective of his telescope. Unbelievable!! Don’t you even think of it! Come see us, we’ll show it to you safely!


Other Objects

Some of the the brighter Messier Objects can be seen dimly at sidewalks from time to time, but you need a large aperture telescope and a good night to see something more than a fuzzy blob. Most of us OAFs will think it is a big deal, but others may be less inspired. Never-the-less if an OAF happens to bring a BIG telescope you might be lucky and see a globular cluster, nebula, or on rare occasions, the core of a comet.

But in general, to get a good view of clusters, nebulae, comets, and galaxies, one needs to observe from a place away from light pollution. Fortunately, OAFs hold monthly public star parties at the Diefenbunker which is dark enough to let us see all those goodies.

What you won’t see from the sidewalk

Some things we just can’t show you:

  • The flag planted on the moon. It’s just too small and far away. This is a frequent question and we’re happy to chat about it.
  • ISS or the shuttle. In general man made satellites move too quickly for us to track with telescopes. (Telescopes are made to move very slowly.) But we can point out when you can see them with your own eyes.
  • UFOs. I can count the number of times I’ve seen them on the tentacles of my ventral gill-cover (i.e. zero).
  • Pluto. Sorry it’s too faint.
  • Galaxies. Sure they have 100 billion stars. But they’re so far away, the glare of a single streetlight blots them out. Come to our darker-sky star party to see galaxies.
  • Something that’s currently below the horizon. That can be any of the objects listed in the “What can you see” section above. The earth simply gets in the way — at least half the time.
  • (We can’t show you those things. But we can chat about them all night.)

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