The Moon is rolling past a trio of bright planets in the early morning sky this week. Tomorrow, Saturn will stand above the Moon. Brilliant Jupiter is to the upper right, with orange Mars to the lower left.

Such a lineup is possible because the Moon and planets are all close to the ecliptic – the Sun’s path across the sky. The alignment isn’t quite perfect, though. The orbit of each body is tilted a bit with respect to the ecliptic, so each of them can appear a little above or below that path.

Right now, Jupiter and Saturn sit almost directly atop the ecliptic. Mars is a degree or so south of it, with the Moon a couple of degrees farther.

The Moon sometimes passes directly between Earth and one of the planets. In fact, it passed in front of Mars just a couple of months ago, blocking the planet from view. Because of the different angles of the orbits, though, such “coverups” don’t happen every time the Moon passes by a planet. Most of the time there’s just a close encounter, as there is with Saturn tomorrow.

The Moon sometimes covers the Sun as well, creating an eclipse. And that’s where the word “ecliptic” comes from. Eclipses can happen only when the Moon is crossing the Sun’s path. If the Moon covers the Sun, it’s a solar eclipse. And if the Moon passes through Earth’s shadow, it’s a lunar eclipse — all made possible by passages across the ecliptic.

We’ll have more about this early morning lineup tomorrow.

Script by Damond Benningfield