In the Sky This Month

The planets Venus and Jupiter are in the dawn sky now. Venus is the brilliant Morning Star. Slightly fainter Jupiter, which is the largest planet in the solar system, stands well to its upper right.

HR 8799 is about 130 light-years from Earth, in the constellation Pegasus. The star is bigger, brighter, and heavier than the Sun. It’s orbited by at least four giant planets, and astronomers have photographed all four of them.

Pegasus is in the eastern sky at nightfall. Astronomers recently discovered a planet orbiting a star in the constellation that’s so close to its parent star that it’s evaporating, leaving a trail of debris that stretches halfway along the planet’s orbit.

Spica poses to the right of the Moon early this evening. The fainter planet Mars is farther to the lower right of the Moon. Although Spica looks like a single star, it consists of at least two stars, both of which are far more impressive than the Sun.

Mars is close to the right or upper right of the Moon in early evening. It looks like a fairly bright star, but it’s so low in the sky that you need a clear horizon to spot it. The star Spica, which is about twice as bright as Mars, is to the upper left of the Moon.

A fetching star cluster comes into view on summer evenings. Messier 11 is more than 6,000 light-years away, in Scutum, the shield. Its brightest stars make the shape of the letter V, resembling a flight of ducks, so M11 is also known as the Wild Duck cluster.

Just north of the teapot-shaped star pattern marking the constellation Sagittarius, small telescopes reveal the Trifid Nebula, a fuzzy pink patch of light. The nebula is a cloud of gas and dust about 4,000 light-years from Earth.

If you watch the stars on a dark night, it’s easy to think of the sky as a great dome. But as the hours pass, the dome rotates. New stars rise in the east, while others vanish in the west. So ancient skywatchers thought of the sky as a sphere that encircles us.

The Moon is “new” tonight as it crosses between Earth and the Sun. It will return to view, as a thin crescent, on Sunday evening, quite low in the west at sunset.

Eos, a recently discovered cloud of gas and dust, spans 40 times the width of the Moon and is only 300 light-years away. But it is extremely faint. It is centered along the border between the northern crown and the head of the serpent.