This is the month that the colorful fall foliage in New England starts transforming our landscape even as our skies shift into their fall and winter constellations. The winter hexagon starts emerging over our eastern horizon a little earlier each night. The bigger picture of cosmology that provides the context within which everything happens that we continually observe is also transforming.

The University of New Hampshire just held its second annual New England Fall Astronomy Festival. The featured speaker was Dr. Alex Fileppenko, a great teacher at the University of California. He was on both teams that discovered the accelerating expansion of the universe — the most astounding and unexpected discovery of the last decade of the 20th century.

Additional Photos

SKY GUIDE: This chart represents the sky as it appears over Maine during October. The stars are shown as they appear at 10:30 p.m. early in the month, at 9:30 p.m. at midmonth and at 8:30 p.m. at month’s end. Jupiter is shown in its midmonth position. Sky chart prepared by George Ayers

His brilliant and entertaining talk was titled “Dark Energy and the Runaway Universe.” He used good slides and great props to make difficult concepts easy to understand. Using precise measurements of type 1A supernovae in distant galaxies, which turned out dimmer than they should have been, given a set rate of expansion of the universe, they determined that the universe is actually expanding at an increasing rate. That accelerated expansion started about 5 billion years ago as galaxy clusters got farther apart from each other and more of this mysterious dark energy was present. It was only discovered 14 years ago but it started happening billions of years ago.

Then he took over an hour’s worth of excellent questions that brought out some of his brilliance in his clear and engaging answers.

There were also several excellent exhibits, including one on IBEX, the interstellar boundary explorer. UNH collaborated with others to build the IBEX and a scientist was there with two detectors explaining how they work. Launched about four years ago, this unique little satellite mapped the invisible boundary of our solar system by detecting neutral atoms generated at the boundary between the heliosphere and interstellar medium.

We actually live inside a giant bubble blown by our 1 million mph solar wind. It extends to about 100 a.u., or about 10 billion miles into space. By comparison, Pluto orbits at about 40 a.u. Scientists used to think there is a bow shock wave at the boundary of our heliosphere with the interstellar medium as we move around our galaxy, similar to the bow-shock around the Earth as it encounters solar wind. Now they found the boundary is much gentler, more like the bow wave in front of a boat as it pushes through still water.

Earlier that night I viewed the sun through an h-alpha filter and saw some sunspots and a solar prominence that was serenely floating just above the edge of the sun. Through a pair of large binoculars, the nearly first-quarter moon was shimmering in its exquisite and fragile beauty.

Mars continues to hang on as our only evening planet. The red planet sets around 7 p.m. Look low in the southwest half an hour after sunset on the evenings of the 16th through the 18th as a slender waxing crescent moon drifts by Mercury and then Mars. Mars is in Scorpius now, just above and to the right of a very similar object named Antares — a red-giant star about 800 times larger than our sun and 15 times more massive. It’s just over 500 light years away, but if you could place Antares where our sun is, its surface would extend to the asteroid belt between Mars and Jupiter.

We lose Saturn early in October. You may be able to spot it in binoculars during the first few evenings this month very low in the west. It will show up again early next month in the morning sky.

Jupiter begins the month rising around 10 p.m. and will rise by 8 by the end of the month. It can be found in Taurus just to the left and below the V-shaped Hyades star cluster marking the face of Taurus and the famous Pleiades or seven sisters on the back of Taurus.

Brilliant Venus rises around 3:30 a.m. and can be seen in Leo. Look for a stunning conjunction of Venus and Regulus one hour before sunrise on the morning of Oct. 3. Venus will be only one-fifth of a degree below Regulus, which is 150 times fainter than the planet.

Then watch a waning crescent moon pass below Venus on the mornings of the 11th through 13th, one hour before sunrise in the eastern sky.

Our two largest asteroids, Ceres and Vesta, will be visible in a telescope in Taurus near Jupiter this month. The Dawn spacecraft just left Vesta after making some amazing discoveries and is heading to Ceres for a February 2015 close encounter. It found signs of water and hydrogen on 330-mile wide Vesta. The hydrogen came from hydrated minerals delivered by carbon-rich space rocks that collided with the asteroid.

OCTOBER HIGHLIGHTS

• Oct. 3. Venus is less than a quarter of a degree below Regulus this morning.

• Oct. 4. On this day in 1957, the Russians launched Sputnik, the first satellite. It was about the size of a beach ball and it only stayed up for three months. The U.S. launched Explorer 1 on Jan. 31, 1958, and it discovered the Van Allen radiation belts around the earth.

• Oct. 5. The moon is just below Jupiter tonight around 11.

• Oct. 7. The Draconid meteor shower peaks, usually only producing about five per hour.

• Oct. 8. Last-quarter moon is at 3:34 a.m.

• Oct. 12. Venus shines near the waning crescent moon this morning.

• Oct. 15. The new moon is at 8:04 a.m.

• Oct. 17. The waxing crescent moon is between Mercury and Mars this evening, half an hour after sunset.

• Oct. 21. First-quarter moon is at 11:33 p.m.

• Oct. 22. The Orionid meteor showers peaks this morning. Caused by Halley’s Comet, it appears as about 20 sand-grain-sized pieces burning up high in our atmosphere each hour this morning.

• Oct. 29. Full moon is at 3:51 p.m. This is also called the Hunter’s Moon.

Bernie Reim of Wells is co-director of the Astronomical Society of Northern New England.

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