The winter Milky Way shines across the sky from east to west in a blaze of starlight.

Roaming through the Milky Way with binoculars is an amazing experience.

It’s like canoeing down a river of golden stars. When we look towards Sagittarius, halfway up the eastern sky, we are looking towards the centre of our galaxy where just about all the stars are old stars and hence cooler. The star colours here are therefore predominantly reddish yellow, whilst the stars in the outer edges of our galaxy are blue and white, advertising their relative youth and energetic spirit.

Most of the prominent stars of summer are getting ready to say farewell to the evening sky over the next few weeks. Stars like Sirius and Procyon are in good view in the west soon after sunset, but it won’t be long before they’ll drop from sight. They’ll move back into the evening sky by late spring, continuing the cycle of seasons in the heavens. And June 21st is the winter solstice. Our shortest day and longest night for the year. It’s a point in Earth’s orbit that marks the beginning of winter in the southern hemisphere and summer in the northern hemisphere.

We have seasons because Earth is tilted on its axis. At the June solstice, the south pole tilts away from the Sun, bringing less sunlight to the southern hemisphere. Six months later, at the December solstice, the south pole tilts sunward, giving the northern half of the globe shorter days and longer nights.
For me, the one constellation that really tells me that winter has arrived is Scorpius, the scorpion, located high in the eastern sky by mid-evening. Look for it on the star chart, and then find yourself a spot away from streetlights, and find it in the sky. It’s one of the few constellations that really resembles what it represents.

All scorpions have claws, except for our scorpion in the sky. As the constellation is configured today, Scorpius has a curving tail; a body, highlighted by bright orange Antares; and a head, marked by a short line of stars. But its claws are gone; and have been for thousands of years.
Yet the stars that represented the claws are still there. And they still bear names related to the scorpion, even though they’re officially in Libra, the balance scales. You can find Libra, above and to the left of Scorpius.

Libra’s 2 brightest stars are Zubenelgenubi and Zubeneschamali. Their names mean the southern and northern claws. Those names tell us that, when Scorpius was first drawn, thousands of years ago, Zubenelgenubi and Zubeneschamali belonged to Scorpius. Later, though, they were assigned to Libra. That’s because the Sun stood in that part of the sky at the September equinox. Day and night are equal then; a time of balance in the heavens. So that region was named for the balance scales. Even though Zubenelgenubi and Zubeneschamali no longer officially belong to Scorpius, it’s still quite easy to see them as its claws.

As our eyes scan further to the northwest, we come to a blue-white star. This is Spica, in the constellation of Virgo. What we see as Spica is actually two heavy stars. One is about 11 times the mass of the Sun, while the other is about seven times the Sun’s mass. Each star is also much bigger than the Sun, and hundreds or thousands of times brighter. For the stars of Spica, life is a never-ending give and take. The stars tug at each other and bombard each other with strong winds.

The stars are so close together that they orbit each other in just four days. Since both stars are big and hot, they produce powerful “winds” of charged particles. The winds collide between the stars, producing X-rays. The combination of the winds and X-rays heats the side of each star that faces the other. And the gravity of each star pulls more strongly at the side of the companion star that faces it. That distorts the stars, so each one is shaped more like an egg than a ball, with the small ends pointing toward each other.

A myriad of other bright stars adorn the late-evening sky right now. Blue-white Regulus, the heart of Leo, the lion, stands half-way up the north-western sky. Yellow-orange Arcturus, one of the brightest stars in the night sky, is well up in the north-east. And all around the heavens, you'll see many other stars in shades of blue, white, yellow, orange, and red.

Each instant that you watch one of these stars, you're participating in the end of a long journey - a journey that began deep inside the star.

Starlight is created in the heart of a star, where atoms join together to create heavier atoms, plus a "packet" of energy called a photon. Few if any of the photons born inside a star make it to the surface. They ram into atoms or other photons, triggering the creation of new photons. Thousands of years after a photon is born inside a star's nuclear furnace, some of its descendants finally reach the surface.

Once there, they rush into space at the speed of light. Photons come in different colours, which reveal the temperature of a star's surface; blue stars are the hottest, red stars are the coolest.

Eventually, some of the light that left Regulus or Arcturus makes its way to Earth. As you look up, some of the starlight strikes your eye - and its journey is at an end.
But the photon triggers one last reaction. A nerve impulse travels to your brain, telling you that you've just seen one of the wonders of nature: a star.

Go outside on any clear night this month, and low in the north-western sky, just at the head of Leo, the lion, you’ll find an interloper. The red/orange star, is not a star, but the Roman god of war, the planet Mars. On the evenings of June 17th and 18th, Mars will be only 1 degree from the star Regulus. Both the star and the planet will be of the same brightness. The red hue of Mars and the bluish hue of Regulus will make a great colour contrast. The view with binoculars will be quite enchanting. Mars is 273 million kilometres away, whilst Regulus is 79 light years away. The light from Mars takes just on 15 minutes to travel the distance to your eye; the light from Regulus has been travelling since the end of WWII.

The month of June also features a planet that’s both bright and quite elusive. Many people, including many astronomers, have never seen the planet at all. The planet is Mercury. It should be easy to find, because it's one of the closest planets to Earth. But Mercury is also the closest planet to the Sun. As a consequence, we see Mercury only when we look near the Sun; low on the horizon just after the Sun sets or just before it rises. This closeness to the Sun makes observing Mercury very difficult.
Temperature variations on Mercury are the most extreme in the solar system ranging from 90 degrees C in shadow to 700 degrees C in full Sun. Hot enough to melt lead!!

If you’re intrigued by this little planet (it’s only 40% the diameter of the Earth), you can catch a glimpse of it during June. The best night to try is June 27th when you can use the Moon as a guide. Look about 45 minutes after sunset, low above the north-western horizon. Locate the 2-day old crescent Moon. Above it and to the left, you’ll notice a bright, orange star. That is Mercury.

The Moon is at First Quarter on June 3rd, Full on the 11th, at Last Quarter on the 19th, and New on June 25th.

Happy observing!