The astronomy news of the week was the discovery of the closest exoplanet yet. What’s more, it could be a pretty nice place. No closer good world will ever be found, because it orbits the very closest star: Proxima Centauri, a dim red dwarf 4.25 light-years away.

Face south-southwest at nightfall this week, point your finger about 20 degrees (two fist-widths at arm’s length) below horizontal, and you’re pointing at it. Proxima b, as the planet is being called, will entice the human race for all time to come.

Proxima itself, also known as Alpha Centauri C, is part of the Alpha Centauri triple-star system. It never comes above the horizon for the latitudes of New England.

But it’s easy this month to see that you’re pointing in the right direction. The Alpha Centauri system is straight down under this summer’s most eye-catching celestial landmark: the triangle of Mars, Saturn, and Antares.

The triangle changes shape a little each day, as Saturn and Antares move westward and Mars hangs back. The Moon will pass over it this Wednesday, Thursday, and Friday.

You’ll notice that Antares, like Proxima Centauri, is a reddish star.

But there the similarities end. Antares is a supergiant, pouring out 65,000 times as much heat and light as the Sun. Proxima emits only 1/600 of the Sun’s heat and light.

As for size? If Proxima were the size of a pea, Antares would be a fireball 13 stories high. Stars tend to be very different from one another.

About that planet. Proxima b is somewhat bigger than Earth, with at least 1.3 Earth masses, maybe 2 or 3 but probably no more. It orbits its red dwarf in just 11 days, so closely that it ought to bask in a moderate, somewhat Earthly temperature allowing rain, rivers, and seas.

That doesn’t mean it actually has them. Red dwarf stars blast out flares of X-rays and stellar wind, especially in their youth. These could have stripped the planet of all atmosphere, leaving it as bare and dry as the moon. Or, like Uranus and Neptune, it may have an atmosphere so thick that any surface way down at the bottom is thousands of degrees hot.

For a modest world four light-years away, further information will not come easily. Chances are it’s not Earth 2.0. But astronomers won’t rest until they find out, no matter how long it takes.

Alan M. MacRobert is a senior editor of Sky & Telescope magazine in Cambridge (SkyandTelescope.com). His Star Watch column appears the first Saturday of every month.