Happiness Is The ‘Habitable Zone’ / Venus And Moon Dazzle

Waves on Lake Superior in Duluth slam into the shoreline Saturday and break into fusillades of spray. Life on a watery planet can be exciting … and scary.  Bob King

This weekend, powerful winds blasting across Lake Superior created monster waves that exploded like bombs when they struck the shore. My daughter Katherine and I spent some time along the lake, leaning into the wind and watching nature have its way on this watery planet. Wind and water bonded dad and daughter in a shared appreciation of the big lake.

Astronomers are constantly on the lookout for planets orbiting within the habitable zones of their host suns. These are places at the right distance from a star where a rocky planet would be warmed enough for liquid water to pool on its surface. Water is quintessential to life on Earth, so if we’re going to start the search for alien life, a watery planet’s a good choice.

These are artistic representations of the top potentially habitable exoplanets ranked from best to worst by the Earth Similarity Index (ESI), a measure of Earth-likeness based on stellar flux and planet size. The closer the value to one the closer its size and stellar flux to terrestrial values. Planets with high ESI values are not necessarily more habitable as habitability depends of other unknown factors such as surface and atmospheric composition. Earth, Mars, Jupiter, and Neptune are shown for scale on the right. PHL@UPR Arecibo

Earth orbits within the sun’s habitable zone. Water does everything here — drips, trickles, percolates, flows, bubbles, sloshes, pools, erodes, shoots, slams and even explodes. The latest tally on the Habitable Exoplanets Catalog lists 53 potential extrasolar planets where liquid water might exist. This is the optimistic number. If we look more conservatively, the tally drops to just 13. The closest watery world beyond the solar system is Proxima Centauri b at 4.2 light years. It circles the star Proxima Centauri, one of three that make up the Alpha Centauri system. Somewhere out there, waves beat a rhythm against the rocky shore under an alien sun.

This lovely scene awaits your gaze Tuesday evening (April 17) at dusk in the western sky. Stellarium

While on the topic of orbs beyond Earth, the returning moon will engage with Venus Tuesday evening (April 17) during evening twilight. The two will be just 5.5° apart and low in the western sky. They’ll look beautiful together especially with the crescent filled out with ghostly earthshine, light reflected from our planet to the moon and back to our eyes. Add in the pretty Pleiades star cluster, the one with stars shaped like a tiny dipper, and you’ve got a great naked eye event.

On Wednesday, the crescent sits squarely inside the Hyades star cluster. Use binoculars for the best view then slide to the right to view the Pleiades (Seven Sisters) in the same. Stellarium

Then on Wednesday (April 18), be sure to face west again in late twilight and early nightfall to catch a thicker crescent moon sitting smack in the middle of the Hyades star cluster. Binoculars will pull in many more stars and give the best view of this interesting alignment.

A man runs from a giant wave crashing on the shore in Duluth’s Canal Park Saturday. Bob King

4 Responses

  1. kevan Hubbard

    Impressive waves yet lake superior is an inland lake.I’m guessing it doesn’t have tides so the waves must be caused by wind?the worlds largest freshwater body,the Caspian sea also seems to have waves driven by winds from the steppes around it.

    1. astrobob

      Hi Kevan,
      Correct. We have a seiche but no tides. This is all wind. Sustained 35-40 mph with gusts to 50 that day.

  2. kevan Hubbard

    Off the true seas the Mediterranean is virtually tideless and the black sea completely. I’d imagine Mediterranean tides are to be found along the western end by the straits of Gibraltar? The red sea has a wider opening at it’s bottom so I’m guessing tides down there?

    1. astrobob

      Interesting thoughts, Kevan. I never thought about tides in the Mediterranean, though west seems more likely than east.

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