For the Moon, it’s another night, another bright companion. After passing close to the brightest star of Gemini and the planet Mars over the past couple of nights, tonight it takes aim at Regulus, the heart of the lion. The star climbs into good view directly below the Moon after midnight. The Moon will move toward the star during the night, so they’ll be much closer at dawn.

The Moon passes near these bright lights because, just like the Moon, they all stay close to the ecliptic. That’s an invisible line that marks the Sun’s annual path across the sky.

The stars all maintain a fixed position relative to the ecliptic – at least on human timescales. Over the millennia, the ecliptic itself actually shifts a little – the result of a slow wobble in Earth’s axis.

The orbits of the Moon and planets are tilted a bit. That causes those bodies to move back and forth across the ecliptic. The planets cross the ecliptic every few months or years.

But the Moon crosses every couple of weeks. It spends two weeks to the north of the ecliptic, then two weeks to the south of it. Tonight, it’s a few degrees to the north. Early Monday, though, it will cross to the southern side. And that will set up an especially close encounter with the next bright light along the ecliptic: Spica the brightest star of Virgo. In fact, the Moon will pass directly in front of the star early Wednesday. We’ll tell you all about that next week.

Script by Damond Benningfield