The night sky: Intergalactic time travel in full view of everyone

By JOHN DUNLOP

Telescopes can see far into space, but even with the naked eye starwatchers can see a galaxy two million light years away.

Galaxies look faint and fuzzy, but are giant collections of stars like the Sun.

This month, four galaxies are visible in the night sky away from the glare of city lights.

The star-clouds of the Milky Way stretch for thousands of light years around us. They move lower in the sky during October evenings, and rise again in the east during the morning.

This motion is due to the daily spin of the earth, and can be tracked by watching the Southern Cross during the night and in the early morning.

At this time of year the Cross starts the evening with the two pointers aiming down at it, and ends the night climbing in the south-southeast with the pointers underneath it.

To use the Cross as a clock, remember its position at, say, 9 pm. The sky appears to spin nearly 360 degrees in 24 hours, so every 2 hours it will spin 30 degrees.

For calendar use, cut out or copy the map above on to card and mount it on the wall with a pin through the South Celestial Pole. This is the point in the sky directly above the South Pole.

The map gives the position of the Cross in the early evening on any date. Spin the map to match the stars and the current month will be at the bottom.

Two other galaxies are easily visible in dark skies over the next few months. The Large and Small Magellanic Clouds (LMC and SMC) look like tiny clouds in the south, between the Cross and the bright star Achernar. Their light has travelled at 300 000 kilometres a second for about 180 000 years to reach us.

Most fine nights a telescope at Mount John Observatory near Lake Tekapo is aimed at the middle of our galaxy and at the LMC and a digital camera photographs them. Data from more than 15 million stars is used to hunt for planets around distant stars, the mysterious dark matter that surrounds our galaxy and stars that vary in brilliance. Details are at www.vuw.ac.nz/scps/moa/

Even with a humble pair of binoculars you can see some LMC detail, including the Tarantula Nebula (pictured above), a huge cloud of glowing hydrogen gas, birthplace of hundreds of massive hot stars.

Spectacular images of this are in our Stardome Spring Sky planetarium show, and our telescopes get a clear view of it. Contact the Observatory on ph 624 1246 or at www.stardome.org.nz

The fourth galaxy can be spotted from Auckland northwards if you have a clear dark view to the north.

The great Andromeda Galaxy rises to its highest position about 1 am this month, or around 11 pm next month.

An easy way to find it is to locate the four bright stars, low in the north, that make a distinctive square a bit larger than an outstretched fist.

This is the great square of Pegasus. Underneath and a little to the right will be a faint oval smudge.

Andromeda is around 2 million light years away, and is one of the few galaxies not rushing away from us at thousands of kilometres a second.

It is moving towards us at about 300 km a second and in a few billion years will cause celestial fireworks as it passes through the Milky Way.