Special stars known as the wanderers are actually planets

O

ne of the distinct advantages of living in the north is an absence of light pollution. Get a few minutes outside of Prince George and the night time sky becomes a marvel.

I am in awe every time I look up and see the Orion’s Belt, the Big Dipper, or the square of Pegasus. It is hard to imagine the light from these stars has travelled for years – tens, thousands, or even millions of years – before it reaches my eye. Looking at the night time sky is time travelling.

No wonder our ancestors were fascinated by the celestial sphere. After all, with no light pollution, they experienced brilliant starscapes almost every night. Even so, the naked eye can only discern about 2,500 stars in the sky at any one time.

Five of those stars are special. They are the wanderers. To ancient stargazers, they moved in patterns discernibly distinct from the rest of the sky. Our ancestors endowed them with almost mystical properties. It took the development of astronomy before we finally understood the wanderers were actually planets.

And it took the invention of the telescope to really get a good picture.

But even with a telescope, the planets still presented mysteries. For example, the rings of Saturn come and go from our perspective. This is related to the relative position of Saturn in its orbit and with respect to us. The disappearance of the rings coincides to viewing them edge on. As the tilt becomes more apparent, the rings become more prominent as seen from Earth.

Astronomy has evolved as the instrumentation has become more sophisticated. It has also taken to space.

The launch of the Hubble Space Telescope opened up the cosmos in a way which could not have been achieved on Earth surface at the time. It showed us billions of galaxies spread out across the whole universe.

Hubble isn’t the only space telescope, though, and each new instrument put into orbit seems to add to the list of our capabilities while expanding our knowledge. In particular, the Kepler Space Telescope was launched in 2009 to look for exoplanets – planets orbiting other stars.

By January 2015, Kepler had confirmed detection of 1,013 exoplanets found in 440 star systems. It had another 3,200 suspected planets on its list. Indeed, since the early 1990s, a total of 3,693 planets have been detected in 2,768 systems by a variety of methods and telescopes.

Simply put, planets are pretty much everywhere we look. Some circle the dying remnants of neutron stars which burned out long ago. Some are found in globular clusters where heavy metals are scarce.

The oldest detected so far is about 13 billion years old – or, at least, the light from its star was released that long ago. The youngest are little more than protoplanetary disks (called “proplyds”) within nebula.

Our galaxy and the billions of others in the universe seem to be relatively well populated with planets. Astronomers have been busy finding exoplanets using a wide variety of techniques to detect exoplanets and not all of these techniques depend on space telescopes. Radio telescopes, for example, can detect the slight oscillation in a stars position resulting from an orbiting mass as a shifting frequency but this tends to only work with exoplanets much larger than Jupiter.

The Kepler Space Telescope keeps track of the light intensity from 145,000 main sequence stars.

Variation in intensity can indicate a planet passing across the face provided the variation has a regular pattern to it. That is, if you were looking at Sol from a neighbouring star, you would see a yearly cycle as Earth passed across the face of the sun.

Of course, with multiple planets in a solar system, things get a lot more complicated but not beyond the reach of astronomers.

Using mathematical techniques, they can deconvolute the collective motions of an entire solar system.

The exploration of the galaxy has appeared to answer the question of whether or not there are other planets. It would appear the answer is overwhelmingly yes. Astronomers have also found a number of planets which reside in the “Goldilocks Zone” – the region around a star where conditions are “just right” for an Earth-type climate with liquid water.

Indeed, spectroscopic analysis has also detected the presence of liquid water on the surface of some exoplanets. The final question is – do any of these exoplanets show signs of life?

Some astronomers have argued water is not a sufficient condition. There must also be land so life can arise at the interface between. It is only with further studies that we will possibly be able to determine if any of the exoplanets already discovered has a surface much like our own.

If so, then we might finally find signs of intelligent life in the universe.