Exoplanets and the search for a Goldilocks planet

An exoplanet, or extrasolar planet, is a planet outside our solar system.  The first confirmed detection of such a planet occurred in 1992 [scientific paper].  Since then there have been 528 confirmed detections (as of 12th February 2011) with many more being added to the list on a constant basis.  A full and updated catalogue of exoplanets can be found at The Extrasolar Planets Encyclopedia.

These planets are so far away and so faint that they can only be detected indirectly.  Various detection methods exist; for example, you can look for a tiny wobble in a stars position caused by the gravitational pull of the orbiting planet, or you can look for a faint dimming of a star’s light as the orbiting planet passes in front.  The NASA Kepler space observatory, launched in 2009, uses the latter method for its mission to discover Earth-like planets orbiting other stars.

The race is now underway to find that first “Earth-like” exoplanet, sometimes dubbed Earth-2.0 or the Goldilocks planet.  Such a discovery seems now inevitable and only a matter of time, but when it comes will nonetheless surely be a moment of profound significance.  This planet would have to be of similar size to the Earth and within an orbiting zone of its star that would allow for the existence of liquid water – the so-called “habitable zone“, and not be tidally locked i.e. not have one side of the planet always facing the star.  Although the exact criteria for an Earth-like planet as well as how and when this discovery is likely to be announced is not altogether clear, see here.

The Kepler space-based telescope has already produced a windfall of potential candidates [scientific paper][BBC article].

Recently published results have thrown up surprising planetary configurations, such as a planetary system comprised of six planets in very close orbit to their star, causing astronomers to rethink theories on how planets are formed [scientific paper][BBC article].

There is still the possibility that a rouge planet (in interstellar space having been ejected from its planetary system) could support an ocean (kept warm by geothermal activity) beneath its frozen surface leaving open the intriguing possibility of life in unexpected corners of the universe.  [scientific study][summary].

The discovery of multiple extrasolar planets (with estimates of at least 40% of solar-type stars having low-mass planets [BBC article]) has intensified interest in the possibility of extraterrestrial life.  I shall leave this discussion for a future post.

 

The Star of Bethlehem

“Where is the one who has been born king of the Jews? We saw his star when it rose and have come to worship him.” Matthew 2:2 (NIV)

“… the star they had seen when it rose went ahead of them until it stopped over the place where the child was.  When they saw the star, they were overjoyed.” Matthew 2:9-10  (NIV)

The Magi travelled from the East in search of the King the star had led them to, but what exactly was this star?  There are three prevailing astronomical explanations for the ‘star’:

1.  A  conjunction of Jupiter and Saturn, such as argued by Hughes, Molnar and Kidger:

Hughes, D.W. – “The Star of Bethlehem” Nature, 1976, 264, 513-517.

Hughes, D.W. – “The Star of Bethlehem” New York: Pocket Books, 1979.

Molnar, M.R. – “The Star of Bethlehem” New Brunswick, N.J.: Rutgers University Press, 1999.

Kidger, M. – “The Star of Bethlehem” Princeton: Princeton University Press, 1999.

2.  A Comet, as argued in

Humphreys, C.J. – “The Star of Bethlehem – A Comet in 5 BC – and the date of the birth of Christ” Q.Jl. R. Astr. Soc., 1991, 32, 389-407.

Humphreys, C.J. – “The Star of Bethlehem”, Science & Christian Belief, 1993, 5, 83-101.

Prof. Sir Colin Humphreys case can be heard in a freely available lecture here.

3.  A supernova or hypernova. This is the case made by Frank J. Tipler who thinks “it must have been a Type 1a supernova or a Type 1c hypernova, located either in the Andromeda Galaxy or, if Type 1a, in a globular cluster of this galaxy” (The Physics of Christianity)

Tipler, F.J. – “The Star of Bethlehem: a Type Ia/Ic Supernova in the Andromeda Galaxy”, Observatory, 2005, 125, 168-174.

In my opinion none of these explanations quite fit all the details, or for that matter the intention of Matthew’s Gospel account.  After all how can an actual star stop directly over a single dwelling place in the small village of Bethlehem!  Naturalistic explanations seem futile.

A nice little video summary, including a simulated Bethlehem night sky, can be view here.