Subzero sun and a glimpse into the future

The sun rises through a bank of lake fog on Lake Superior near the Lester River on a bitter cold Thursday morning here in Duluth, Minn. Photo: Bob King

It wasn’t easy to feel the sun this morning with 19 below zero and a sharp northwest wind. No matter what the season, the sun’s brilliance remains the same, but you’ll strain to sense the warmer side of its personality on days like today. When the thermometer scrapes bottom in my town, Lake Superior exhales foggy breath just like people do. We call it lake steam or ice fog. Colder air blowing over the warmer open water suddenly drops in temperature; the water it’s carrying condenses into millions of wispy vapors. The swirls combine into clouds that rise into a tidal wave of steam in the distance. Raw, menacing, ethereal – pick your adjective. We love the apparition and consider it one of the many intangible reasons we choose to live here.

Photo of the sun taken at noon CST today by the Solar Dynamics Observatory. Several sunspot groups are visible including the lively 1401. Credit: NASA

After a period of doldrums, solar activity is picking up again with several picturesque and magnetically active sunspot groups dotting the sun’s face. In particular, Region 1401 has a busy, complicated mix of magnetic polarities (north and south magnetic poles) that’s been responsible for an ongoing series of flares. Once the group rotates more directly into our line of sight, we might see some effects on Earth. Meanwhile material from a January 16 coronal mass ejection (CME) is expected to touch our planet starting late tonight through the 20th. That means an increased chance for northern lights for observers at higher latitudes. If you live in the northern U.S. or southern Canada, it’s worth checking the northern sky both nights.

The Ring Nebula in the constellation Lyra is a classic example a planetary nebula. The remaining white dwarf is at center is the size of Earth but contains 1.2 x the mass of the sun. Credit: NASA/ESA

The sun is a middle-aged star with about five billion years of an active, exciting life remaining before it runs out of nuclear fuel. In the year 5,000,000,001 A.D. – give or take – the sun will sheds its outer layers to reveal a carefully kept secret – a tiny, compressed core called a white dwarf star. Though only as big as the Earth, a white dwarf is twice as hot and so fantastically dense that a teaspoon of the stuff would weigh as much as an elephant. Surrounding the dwarf will be a butterfly or ring-shaped cloud of gas astronomers call a planetary nebula. The name comes from its resemblance to the round shape of a planet.

The scenic cloud are the remains of the sun’s outer layers that will be expelled by powerful stellar winds during its tumultuous transition to white dwarfdom. Every time we observe a planetary nebula through our telescopes, we see the sun’s distant future.

ESO's Visible and Infrared Survey Telescope for Astronomy (VISTA) captured this unusual view of the Helix Nebula, a planetary nebula located 700 light-years away. The left picture was made through infrared filters. The telescope's infrared vision reveals strands of cold nebular gas that are mostly obscured in visible images of the Helix. Click to enlarge. Credit: ESO/VISTA/J. Emerson

European astronomers released a brand new photo today of the Helix planetary nebula in the constellation Aquarius taken in infrared light. The main ring of the Helix is two light years across and glows due to excitation from strong ultraviolet light emitted by the white dwarf at center. Each of the fine strands radiating from the nebula’s center span the size of our solar system and is composed of hydrogen molecules. To learn more about the Helix, please click HERE.

Assuming the Earth survives until the time the sun becomes a white dwarf, we’ll still revolve around it as always, but what we call “sun” will be only a pinpoint of white fire in a twilight-dark sky.

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