Star Spy: Outshining Mars

03:34, Jun 18 2012
Reflected Nebula
A close-up of the Antares region.
Scorpius Region
Scorpius region.
Scorpius Region
Scorpius region.
Scorpius Region
Scorpius Region.

Arcturus competes for our attention

This bright orange star dominates the northern sky and outshines Mars, following a few hours behind (east of) the red planet. Both appear orange, but for very different reasons.

Mars is a rusty planet so looks red in the light of the Sun. Arcturus is a huge red-giant star that dwarfs our Sun, but also is cooler so it radiates a redder light.

The brightest star in the northern hemisphere, it was called Hokule'a, Star of Joy, by ancient Polynesian seafarers.

On the big island of Hawaii, Arcturus was seen directly overhead in the summer, and guided their double-hulled canoes to the island's eastern shores.

If you are outside looking north/northwest, that is Arcturus shining brightly in front of you, about one third to halfway up the sky.

About one hand width (fingers spread out) to the left you can find dimmer Mars.

About the same distance up from Arcturus is Saturn, perhaps half a pinky-finger-length below the star Spica.

Mars and Saturn together with Arcturus form a bright triangle reaching across the north in the earlier hours of darkness.

Arcturus also outshines orangish Antares, which you can locate at the heart of the constellation Scorpius in the image, or above your right shoulder while you stand outside facing north.

Antares is massive, and dwarfs even huge Arcturus, but being about 15 times farther away from us, it is not as bright in our sky.

Colourful clouds of gas and dust are revealed in the deeper image of Antares, the bright yellow star on the right, and the region around it.

Mercury, the dim 'Evening Star'

We call Venus the 'Morning Star' and 'Evening Star' because it always either follows the Sun after it sets, or precedes it in the dawn sky.

Of course we know it isn't a star, rather a brilliant planet shining in the light of the never-too-distant Sun.

But we usually don't even notice the planet Mercury, which, though much dimmer than Venus, also follows and precedes the Sun in our sky.

This week and next the Sun will set between about 4.50pm and 5.35pm, depending on where you are in the country.

If you make a mental note of exactly where the Sun drops below your horizon, and look out above the same spot around 30-45 minutes later, you may see tiny Mercury shining there in the dimming glow from the Sun.

You will be able to follow it from day to day, seeing it rise a little higher and later each night.

The Sun and Moon

New moon on the 20th is when the moon is between Earth and the Sun so is not visible.

But it will return as a very slim crescent the next day, to the left of Mercury, and setting about an hour and a half after the Sun.

The 21st is also the winter solstice, when the Sun reaches its lowest point in our northern sky.

After the solstice the Sun will slowly begin to make its way back south in the sky, bringing us more warmth and longer daylight hours.