Betelgeuse Betelgeuse Betelgeuse!

You may have heard that Betelgeuse, one of the brightest stars in the night sky, is fading. The orange star forms the top left corner of Orion, probably winter's most easily recognizable constellations. Prior to this dramatic dimming, Betelgeuse was in the top ten brightest stars. Now it doesn't even crack the top 25. It's been clear the last few nights, and it seems to me that Betelgeuse is a little brighter than it had been, but it may be a matter of lighting since I live in civilization.
While the star will certainly end its stellar life with a supernova explosion, astronomers are fairly certain that won't be happening any time soon. Betelgeuse is a variable star, meaning its brightness changes, but that change isn't usually this noticeable or long-lasting. Current trending possibilities for the dimming are an ejection of dust or a cool surface area.

Betelgeuse's location in Orion (Constellation Guide)

If a cloud of dust came between Betelgeuse and Earth, that would obscure light from the star and make it appear dimmer. It could be an interstellar cloud or material ejected from Betelgeuse itself. The cool area on Betelgeuse's surface wold have to be very large to cause a noticeable dimming here on Earth. That cool spot would be similar to the sunspots we get on our own star, only much larger.
If Betelgeuse were to go supernova, it would be the event of a lifetime. In brightness, it would nearly match a full moon for months. It would be visible during the day for about a year.
This week's information comes from AccuWeather.

A Star Is Born

Stars are the most common object in the night sky. They come in different colors and brightness. Grab a pair of binoculars and the number you can see goes from too many to count to more than you thought possible. It seems as though they've always been there, but where did they come from?

Orion Nebula, a stellar nursery (NASA)

Gas and dust in space pulled together by gravity attract more material. More mass has more gravity, so it continues to attract more material, while also collapsing into itself. As it collapses and becomes more dense, it begins to hear up. At some point, what is now considered a core begins to fuse hydrogen atoms into helium. The pressure of the energy radiating from the new star is enough to keep it from collapsing into itself further.
Not all of the gas and dust gets sucked into the star. It will swirl around the star and conceal into planets and asteroids, like what happened here in our solar system. In other systems, multiple stars may form rather than just one like we got stuck with.

Life cycle of a star (NASA)

If a star is massive enough, it will blow itself apart in a supernova. Gas and dust from the exploding star will fly out into space and the process will begin again. This week's information comes from NASA.

Star of Wonder

Science is very good at explaining things and can even solve a mystery that has no remaining witnesses. Science is able to tell us how long ago a frozen cave man lived, and even how he died. One mystery that science has been unable to explain, but has offered many possible solutions to, is the Star of Bethlehem that the Magi followed. The star is mentioned in the gospels, and many biblical events have been confirmed by archaeology. But is the star a legend, a myth, a miracle, or something perfectly logical?

There are several astronomical phenomena that could explain the star. People at the time were very astute when it came to sky watching, as the stars and moon were (and still are) great navigational aids, so anything out of the ordinary appearing in the sky would have been noticed and documented. Some examples of astronomical phenomena that could have occurred on the First Noel include a planetary conjunction, a nova, a supernova, and a comet.

A planetary conjunction is when two or more planets appear very close to each other in the night sky, and may even appear to be a single object. Just such an event- a Jupiter and Saturn conjunction- took place in the year 7 BC, just outside the accepted date of Jesus’s birth (6 BC- 4 BC). The timing is very close and the position in the sky is correct, but the planets were not close enough to appear as a single star and while the conjunction may have led the Magi in the general direction of Bethlehem from Jerusalem, but did not stand over Bethlehem as stated in the Bible. 

Conjunction of Venus and Jupiter, 2015

A nova (“new star”) is star that suddenly flares up many times in magnitude. It is given this term because in most cases, it is a star that ordinarily is not visible to the naked eye. Similar to a nova is a supernova, a star which has exploded. Chinese and Korean records indicate either a nova or supernova occurred in the year 5 BC, which also fits the timeframe for the nativity. Unlike the planets, however, a nova or supernova would remain in a fixed position in the sky. 

Remnants of 1987 supernova (NASA)

A comet is best described as a dirty snowball orbiting the sun. Depending on location and trajectory, they can become visible to the naked eye as they approach the sun. The period of visibility and brightness vary from comet to comet, but as an object in orbit, it would certainly move about the sky. Chinese records indicate a comet appearing in the year 5 BC, which is within the accepted time of Jesus’s birth. The comet’s location in the sky would have it preceding the Magi first to Jerusalem, then to Bethlehem. It even appeared during spring, which is when it is believed he was born, even though we celebrate Christmas in December. That’s a different story for a different blog. 

Comet ISON (NASA)

Over 2000 years later, the great mystery of the Star of Bethlehem may finally have an answer thanks to forensic astronomy and the meticulous records of the Chinese. Was it really a comet, a completely rational cosmic occurrence, which led the Magi to Bethlehem? If so, did divine intervention place the comet where it needed to be at the right time? That question might never be answered.

This week's information comes from two sources. Speculation about conjunctions and comets comes from Colin J. Humphreys and the speculation about novae and supernovae comes from Mark Kidger.