Most of these objects are far too faint, or far too small, to see from a city — some are invisible to any telescope ever built. But the wreckage they leave, or the glowing gas around them, often is pointable from our deck. Here is what is really out there, brightest and gentlest first.
A nebula is a vast cloud of gas and dust between the stars — some are cradles where new stars are switching on, others are the ashes of stars that have died. They are the one class here you can genuinely see, and they are what the Seestar loves. Astronomers sort them into five main kinds, in two families: three diffuse nebulae — loose interstellar clouds with no sharp edge (emission, reflection and dark) — and two that mark a single star's death (planetary nebulae and supernova remnants).
When a star far heavier than the Sun runs out of fuel, its core collapses so violently that protons and electrons are crushed together into neutrons. What is left is a neutron star: about one and a half times the Sun's mass, squeezed into a ball roughly the size of Singapore — about 20 km across.
A rare, even fiercer kind is the magnetar — a young neutron star wrapped in the strongest magnetic field known anywhere, a thousand-trillion times Earth's. A single "starquake" on one can flood the galaxy with more gamma rays in a tenth of a second than the Sun pours out in 100,000 years.
You cannot see the neutron star itself — it is a 20 km speck 6,500 light-years away. But you can point at the glowing wreck around it.
Collapse an even heavier star and not even neutrons can hold the core up. It falls in on itself without limit, warping space so steeply that within a certain radius — the event horizon — nothing can escape, not even light. That is a black hole. It is not a thing you can see; it is a region you cannot see out of.
Since 2015 we also catch them a completely different way: when two black holes spiral together and merge, they shake spacetime itself, and detectors like LIGO feel the ripple wash over Earth — gravitational waves, a "sound" from black holes we could never see.
At the centre of almost every large galaxy sits a black hole millions or billions of times the Sun's mass — no one is fully sure how they got so big. Our own Milky Way has one: Sagittarius A*, about 4 million solar masses, 27,000 light-years away in the direction of the Teapot of Sagittarius. Its event horizon alone is wider than the orbit of Mercury.
When the Milky Way's core rides high on winter and mid-year evenings, you are looking straight toward a four-million-Sun black hole. You will only ever see the crowded starfields around it — but it is there, and it is ours.