Health & Family

Mars will pass near Saturn in Thursday night sky

A close encounter happens Thursday evening as Mars comes to within less than a degree (two moon-widths) from Saturn.

This will be best seen in the deepening twilight about 9:30, when it will already be down to 10 degrees above the western horizon. That's a fist-width at arm's length, so you may have to scout out a good horizon.

For early risers, Mercury is the “morning star” appearing in the morning twilight. It reached its greatest angle from the sun on the first of the month but it will still be getting brighter.

It is swinging around the sun, and will appear lower in the dawn sky until it disappears by the end of the month.

It is on the far side of the sun from us on the 29th and will reappear very low in the evening sky in August.

Between our bookends of dusk and dawn planets, we find Jupiter crossing the sky all night. It is opposite the sun in the sky. So it rises at sunset and reaches its highest position, almost 30 degrees above the southern horizon, at 1 a.m. (It's not at midnight, when you might expect it, because we add an hour for daylight time.)

If it felt warm this past week, it was not due to being closer to the sun. We were actually at our farthest from the sun on July 4.

The seasons are caused by the tilt of the Earth's axis, which causes sunlight to be spread out over more area in winter and concentrated in the summer.