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January’s astronomical sights

Josef Borg captured this beautiful shot of Venus as it approaches the horizon to set in the western sky. The planet was so bright that it created a reflection in the sea at Dwejra, Gozo.

Josef Borg captured this beautiful shot of Venus as it approaches the horizon to set in the western sky. The planet was so bright that it created a reflection in the sea at Dwejra, Gozo.

The new year starts off with the bright planet Venus dominating the western sky after sunset. Look at the sky tonight and tomorrow evening to see the waxing crescent moon glide past Venus, which shines brightly to its upper left-hand side tonight. On Tuesday evening the moon will then be to the upper left of Mars.

Venus has been visible for much of last month and will be reaching its greatest distance from the setting sun on January 12. This is called its greatest elongation; it is when, through a small telescope, it appears to be half-lit by the sun, similar to how a first-quarter moon appears from the Earth.

Venus shows phases as it travels along its orbit and gets lit from different angles by the sun. The first known observations of these phases of Venus were made by Galileo Galilei in 1610.

It rises higher in the southwest sky in the coming weeks as it approaches its maximum brightness by the end of January. It also moves in closer and closer to the planet Mars (fainter) and at the end of the month they will be close to one another.

However, apart from Venus, Mars will still be the second brightest celestial object in this part of the sky. The red planet, however, will only return to favourable viewing in July 2018.

January night skies also see some familiar winter constellations, such as Orion (the hunter) high in the south, with its bright red star Betelgeuse to the top left, and white star Rigel (bottom right). The three stars of Orion’s belt, aligned nearly in a straight line, are easy to identify. Below them lies a misty patch – the Great Nebula of Orion – which is home to new stars being formed right now. It is around 30 light years across.

Summer constellations like Cygnus and Lyra can be seen slipping into the western horizon just as it gets dark enough. Just after midnight we will be able to see the giant planet Jupiter rising in the east.

Jupiter has been brightening slowly as it continues to approach the Earth in the coming months. In April, the orbits of the Earth and that of Jupiter, whilst still hundreds of millions of kilometres apart, will bring them close to each other such that the giant planet will be the brightest planet in the sky.

During this year, Jupiter will remain just a short distance away from the bright star Spica, in the constellation Virgo. In fact, on January 20, it will be very close to this star in the early morning hours.

A few hours later, before dawn, we are able to catch up with Saturn. By the end of January, Saturn will rise a few hours before sunrise; however, lurking in the morning twilight there is also the small planet Mercury, which will unfortunately be quite low in the sky this time around and will be very difficult to spot.

The early morning hours on Tuesday will also provide a good opportunity to observe the Quadrantid meteor shower, weather permitting.

On Wednesday the Earth will be at perihelion – the closest to the sun in its orbit in space. On this day we will be just over 147 million kilometres away from the sun – as opposed to the aphelion position in July when the Earth will be over 152 million kilometres away. That’s a difference of nearly five million kilometres, which, however, does not affect our seasonal weather variations so much as the tilt of the Earth on its axis.

This month’s highlights

• Bright planet Venus in the evening twilight.

• The faint winter Milky Way visible high overhead on moonless, dark nights.

• The Andromeda galaxy and the Orion Nebula visible to the naked eye from dark locations.

These events and more on the Sky Almanac 2017 are available from the Astronomical Society of Malta.

www.maltastro.org

Calendar of upcoming events

January 2: The moon close to Venus.
3: The moon close to Mars.
4: Perihelion – the Earth closest to the sun.
5: First quarter moon.
10: Moon perigee: 363,200km away.
12: Full moon.
19: The moon close to Jupiter (before sunrise).
19: Last quarter moon.
22: Moon apogee: 404, 900km away.
28: New moon.
31: The moon close to Venus.

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