Last month, our resident astronomer Luna posed this puzzle: “Earth’s temperature is vastly warmer than physicists would predict, based on just the sun’s rays. Our planet’s average temperature should be -2 degrees Fahrenheit, fully 34° -below- water’s freezing point. Brazil ought to look like Antarctica. What keeps our planet at a comfortable average of 57°?” Here’s the answer, as a Q&A with Luna.

F: So, why do we average 59 degrees warmer than we ought to be?

L: Because our atmosphere holds extra heat.

F: Held by nitrogen and oxygen, which are 99% of our air?

L: Nice try, Frank, but those gases hold NO heat. On their own, our planet would be completely iced over. That happened twice, about 710 and 640 million years ago; it’s called Snowball Earth. The earth’s temperature is made comfortable by a trace gas, carbon dioxide, with an assist from water vapor and methane. This month’s picture shows how CO2 works.

F: Wow. CO2 is how much of the atmosphere?

L: Only 0.035%. That tiny amount is literally our planet’s thermostat.

F: So, CO2 is… good…?

L: Up to a point. As the old hair cream ad line went, “A Little Dab’ll Do Ya.” Until the industrial age, only 280 parts per million of CO2 in our air kept us comfy. We humans have now dumped in 1.5 trillion tons of our own CO2, boosting its level to 420 ppm, a 50 per cent increase that’s generating daily disasters.

F: But fossil fuels are cheap.

L: They are cheap because producers pocket profits while off-loading their pollution costs onto all of us regular folks, using our air as their free trash dump.

F: But we’re reducing CO2, right?

L: Frank, wake up and smell the CO2 curve. It’s getting steeper! The accelerating CO2 increase is accelerating our heating.

F: What about China?

L: China currently emits more CO2 than America, but it didn’t belch out the bulk of the existing, increased CO2. This isn’t a Them-Us Problem; it’s a We-All Problem. Google “Earthrise Apollo 8,” arguably the world’s most famous picture. That’s us there, all together, on a blue dot in space. Either we get all hands on deck and solve this, or we all are going down together, planet-wide.

F: Can we suck the CO2 back up?

L: Recovery makes about as much CO2 as it removes. We’ve got to spew out less. Electric vehicles and wind, solar and nuclear power get us the best bang for our buck. They are the only realistic ways to roll off CO2 before we all end up on the deck of the Titanic.

F: All hands on deck? The Titanic? Maybe a little over-dramatic there, Luna?

L: Warming ocean temperatures and melting ice are rapidly boosting sea levels and killing reefs; more-energetic storms are killing more people; droughts and lethal heat domes are worsening; mega-wildfires are toasting and choking us; and our food production is at risk. Resulting social instabilities are making millions of people into refugees and threatening democracies. We used to have more time. Now we don’t. Do we, as the allegedly intelligent species that’s made this mess, cut CO2 while we still have a fighting chance? The clock is running, Frank. We-all decide.

Backyard Astronomy Talk Series: This correspondent’s next talk, “How Far is That Star,” will be at the Nederland Library at 7 p.m. on September 6. Details and free registration at https:// nederland.colibraries.org/backyardastronomy/.

Also in August skies

The sun begins the month in Cancer, entering Leo on August 10. At mid-month, days and nights are 13.5 and 10.5 hours long, respectively.

The moon’s dates are: Full (Sturgeon or Corn) Moon August 1; Last Quarter August 8; New August 16; First Quarter August 24. A second Full Moon (called a Blue Moon) is August 30.

August Meteor Showers: The Perseids (parent Comet Swift-Tuttle) and kappa-Cygnids (parent possibly Asteroid 2001 MG1) peak on August 13 and 18. The famous Perseids are best seen shortly before dawn. The k-Cygnids peak around 11 p.m.

Best Sky Viewing Nights (Minimal Moon): August 8-23.

Sunset (Mid-Month): Deneb is high in the east; Vega is nearly overhead; and Altair is mid-sky in the northeast. Hercules with its striking M-13 globular cluster is overhead. Libra (twin bright stars Zubeneschamali and Zubenelgenubi) is low in the southwest. Antares is due south in Scorpius.

Midnight (Mid-Month): The Teapot in Sagittarius, marking the center of the Milky Way, glows in the south-southwest. Scan its wonders with binoculars or a telescope.

Sunrise (Mid-Month): The Gemini twins are low in the east. Our nearest neighbor galaxy, M-31 Andromeda, gives great binocular viewing directly overhead.

Mercury has good viewing in August’s first days, low in the west at sunset. Watch it from the western end of Barker Reservoir.

Venus is lost in the sun.

Mars, now small in telescopes, conjuncts with the moon August 18.

Jupiter rises around 11:30 p.m. and is high in the southeast at sunrise. It conjuncts with the moon on August 8.

Saturn rises around 10:30 p.m. and is high in the southwest at dawn. Opposition August 27.

Notable Space Missions: A Northrop Grumman robotic ship resupplies the International Space Station on August 2; a four-person crew launches to the ISS on August 15 on a Falcon 9 booster. India’s Chandrayaan-3 moon lander, with rover, pads down in the lunar south polar region about August 23. The Parker Solar Probe performs a gravity-assist maneuver at Venus on August 21, tightening its orbit around the sun.

Frank Sanders, a spectrum scientist at the U.S. Department of Commerce in Boulder, takes astronomy-related inquiries at backyardastronomy1@gmail.com.