October has a lot going for starwatchers and other appreciators of nature at night. Never mind this weekend’s rain; October nights are especially clear on average. Darkness arrives early, the hazes and mosquitoes of summer are mostly gone, but it’s not yet winter.

So what’s to see up there these evenings? It depends where you look.

The whole southeastern side of the sky appears almost blank through the light pollution inside Route 128. This celestial realm is known as the Great Water, home to big, dim, water-themed constellations: Capricornus the Sea Goat, Aquarius the Water Pourer, Pisces the Two Fish, and just nosing above the horizon, Cetus the Whale.

Good luck picking them out.

Elsewhere things are more interesting. Turn east and face high, and unless your light pollution is truly awful, you’ll find the Great Square of Pegasus, emblem of fall. It’s part of the flying horse of Greek myth.

Look for a square a little larger than your fist held at arm’s length, tipped up onto one corner.

The Square is supposed to be the front half of the horse’s body. Save the rest for a night in country darkness.

From the square’s left corner, a line of three or four stars extends left and slightly down. This is the profile outline of Andromeda, damsel in distress of Greek legend. The left-corner star is her head, the rest of the line is her backbone and one leg, the other, dimmer leg is raised and bent at the knee, and her outstretched arm is supposed to be chained to a rock. We’ve drawn her whole big stick figure in case you have a dark enough sky to piece it out this week or next.

Andromeda is most famous for what’s just off her upraised knee. Look for a hazy little dim-gray glow, like an escaped oval tuft of Milky Way.

The tuft looks like that for a reason. It’s the Great Andromeda Galaxy, an approximate twin of our own Milky Way Galaxy but 2.5 million light-years distant. If any creatures there have eyes like ours and clear nights, they’re seeing our own galaxy looking about like that.

A pair of binoculars makes it easier to spot, but even the view in a telescope is underwhelming from Eastern Massachusetts. It doesn’t look like the enormous thing, striped with two black bands, that 19th- century astronomers drew before photography revealed its true form.

Last summer I got a proper view, black stripes and all, from the Summer Star Party — a big annual amateur-astronomy gathering in Plainfield, in the dark northern Berkshires. A group of New York amateurs brought a towering 20-inch telescope. Lines of people at night waited to climb a tall stepladder to its eyepiece.

The Andromeda Galaxy was, finally, breathtaking.

But it still was nowhere near as clear as a photograph.

The fact is, our eyes are not meant for looking into space. They evolved to work with things right around us on Earth, things that might affect us. The stars don’t. So it’s a lucky fluke that we can see them at all.

The invention of photography was a turning point for astronomy. Today you can find dazzling observatory photos by the thousands. But what you’re looking at is what you would see if you had eyeballs as big as houses, with light-gathering pupils as wide as garage doors, and electronic retinas thousands of times more sensitive than the retinas nature gave you. And swappable retinas that work in the infrared and ultraviolet where humans can’t see.

So, that dazzling Hubble Space Telescope panorama of the Eta Carinae Nebula is not what you would see even if you were right there looking out the window of a starship. It’s what the camera system of the Hubble would see looking out the window.

“What’s that . . . thing?” my wife, Abby, called from the front step last week. It was late twilight, and she was looking west. “There in the sky.”

“Must be Venus,” I called back.

“I know Venus,” she replied. “This is too bright.”

Abby knows the sky. She can spot Delphinus, the Teapot, the wound on the flank of the Bull, and much else. When we met, the care and attention with which she examined the globular cluster M13 though my telescope helped me realize she was a keeper.

I went and looked. It was Venus. But the night was especially clear, and Venus has been brightening and climbing high into thinner air this spring. It was unusually striking. And in May it brightens a little further.

Venus is swinging along its fast orbit around the Sun and catching up with the slower Earth. Right now it’s heading almost straight at us.

That’s why it’s getting bigger and brighter. But come June, it will start to curve away and head down toward the sunset, on its way to passing between us and the sun in August.

Venus isn’t all that big — it’s slightly smaller than Earth. But it’s closer to us than any other planet most of the time, and its global blanket of white cloud is lit by sunlight almost twice as bright as sunlight on Earth. So it can be quite a show.

Shining very high to Venus’s upper left this month (off the chart here) is another cloud-covered planet: giant Jupiter, taking second place for brightness and perhaps jealous of Venus. It’s 12 times bigger in diameter, but it lives seven times as far from the sun where the illuminating light is only 2 percent as bright.

Look way down to Venus’s lower right in twilight this week and there will be a third planet, Mercury. It’s only half Venus’s size, and its surface is dark gray. But sunlight on it is almost twice as intense as even at Venus, which is why we see Mercury as much of anything at all.

Watch Mercury fade day by day; it’s showing us more of its night side as it moves in orbit. If you have very clear air, binoculars may show the Pleiades star cluster to Mercury’s right this weekend. Aldebaran, the eye of Taurus the Bull, twinkles left of Mercury and straight under Venus. Like Capella high to Venus’s upper right, it’s a giant sun shining by light of its own, hundreds of thousands of times farther away.