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Borneo Day 2: Saturday, July 22, 2017

Southern cross

The Southern Cross and Coalsack Nebula, the smallest of all 88 constellations. Seeing it for the first time was a bucket list item of mine.

Yesterday was too cloudy to see the stars clearly, as was every day in Jakarta since we arrived. But today the sky was mostly clear at sunset, so I used my Stellarium software to look up the southern nighttime skies.

Southern Cross and Rigel Kent

Star chart from Stellarium. I used this software to chart out where Alpha Centauri and the Southern Cross were in the sky, south of Scorpio (or Maui’s Fishhook).

Overall the southern skies are less interesting than the north, with fewer bright stars. One of these bright stars is Rigel Kentaurus, or the Foot of the Centaur. It can be found to the southwest of Scorpio next to another bright star called Hadar. We know them more often by their Bayer designations: Alpha and Beta Centauri.

If you follow the line from Alpha through Beta Centauri and continue further you come to three medium bright stars with a fourth somewhat dimmer star that form a kite or cross shape. We call these the Southern Cross.

Scorpio and Centaruus

The general area of the sky, with Scorpio and Centaurus, which surrounds Crux, the Southern Cross.

With the stars’ positions fixed in my mind, I walked outside to the hotel’s parking lot and found a spot with fewer overhead lights. I found Scorpio, and at this latitude (and the latitude of the Polynesian islands) it hung down in the sky like a giant fishhook – Maui’s fishhook. I could see two bright stars to the south, one a yellowish color and the second a brighter bluish color. Alpha and Beta Centauri.

Beyond was the four stars in a cross shape, although the fourth is hard to see with the lights of the city and haze of the tropics. By brightness, the southern tip is Acrux, then the left star is Mimosa or Beta Cruxis, then the top star is Gacrux or Gamma Cruxis. The fourth star (on the right) is known as Delta Cruxis.

I was seeing these stars for the first time in my life. There is a song about this – written and performed by Crosby, Stills, and Nash in their 1982 album. It is called Southern Cross, and the second verse starts out:

Southern_Cross_(Crosby,_Stills_and_Nash_song)

Cover for the 45 rpm single of Southern Cross, by Crosby, Stills, and Nash.

When you see the Southern Cross for the first time,
You understand now why you came this way.

It has been a long-standing bucket list item for me to see Alpha Centauri and the Southern Cross. I stood there alone, amazed for this opportunity, and understanding that Alpha Centauri is actually a triple star, including the closest known star to us: Proxima Centauri, which is now known to have a planet orbiting in the habitable zone. Although it is tidally locked, life could exist there. And I was looking at it, or at least in its general direction.

Picture saved with settings applied.

The Coalsack Nebula, a dark nebula (non-emitting cloud of gas) near Cruxis. It figures prominently in one of my favorite novels, The Mote in God’s Eye by Larry Niven and Jerry Pournelle.

I felt a bit sorry for the many people walking about in this city and elsewhere in the southern hemisphere who know nothing about this, which I have traveled halfway around the world to see.

Jewel_Box_cluster

The Jewel Box, a small open cluster in Crux, the Southern Cross.

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