Earth as seen from DSCOVR, Credit: NASA's Goddard Space Flight Center

Our Pale Blue Dot

One of the benefits of planetary science is the perspective it provides of our home planet, and an appreciation of its fragility in space. The Apollo astronauts marveled at the spectacle of this lovely blue and white marble, suspended above the lunar horizon – an oasis of color in a vast ocean of blackness. As we explore the other worlds in our solar system, it becomes readily apparent that even in the most dystopian conditions we can imagine, a war-torn, polluted, irradiated Earth in the midst of nuclear winter would still be a paradise compared to the extreme, inhospitable environments we find on Mars and Venus, our closest neighbors in space.

A Tale of Three Planets

Living on Mars would be orders of magnitude more difficult than moving to Antarctica, for example. There’s no air to breath on Mars; the average temperature is −63 °C, the dust is toxic, the surface is blasted with hazardous radiation from space, there is no surface water – need I continue?

Husband Hill, Mars, Credit: NASA


  • Venus is even worse, with hellish conditions on the surface due to what’s called a runaway greenhouse effect. Having an atmosphere is generally a huge blessing for life. Without a blanket of air to keep us warm at night, temperatures on Earth would plummet to below −100 °C and then soar to 121°C (250°F) in the daytime, just as they do on the Moon.

    It’s the so-called greenhouse gases in the atmosphere that help regulate the temperature, acting as a protective blanket against the harshness of space. The predominant greenhouse gas in the atmospheres of both Venus and Earth is carbon dioxide. The difference is that while Earth’s atmosphere is 0.04 percent CO₂, on Venus, it constitutes 95%. Even though only a tiny fraction of the air we breathe is CO₂, it has an outsized effect in keeping us warm – like a super-efficient comforter.

  • Artistic rendition of the surface of Venus; light is refracted by the dense atmosphere, bending the horizon into a bowl shape. (Image generated using AI tools based on scientific data.)

Carl Sagan testifying before Congress in 1985 on climate change.

Planetary scientists were among the first to realize that increasing levels of CO2 in our atmosphere could bring about serious, problematic changes in our climate. Venus became a poster child for the worst case scenario – when greenhouse gases build up in the atmosphere to such a degree that your ocean completely evaporates, and the surface becomes hot enough to melt a block of lead.

If you could manage to survive on the surface for more than a few seconds, you’d find yourself subject to crushing atmospheric pressures – like being submerged in Earth’s ocean at a depth of 3,000 ft. In this dark and gloomy place, the light around you is constantly warped by the dense atmosphere, making it seem like you’re standing in a bowl.

The Need to Act

  • As a planet, Earth is not immune to the effects of increased greenhouse gas emissions. The energy trapped by human-produced CO2 has caused average global temperatures to rise. This has a disruptive effect on global systems, creating increasingly hazardous conditions for us and the other animals with whom we share the planet.

    The situation is likely to get worse, because up to this point our oceans have absorbed the bulk of the CO2 released, but the rate of that absorption is slowing down.

    We need to drastically reduce our CO2 emissions, and to do that we must focus on the two biggest sources of greenhouse gases – energy production and transportation.

  • In short, we need to completely move away from gasoline and diesel as quickly as possible, as well as ensure that our energy grid is fed with clean energy sources.

    The good news is that electric vehicles are now a viable alternative to gasoline cars, with the right incentives and infrastructure. On the energy side, solar and wind in tandem with battery storage are already more affordable and safer than fossil fuel alternatives, so the switch to clean energy is increasingly a no-brainer for industry.


    We are proud to say that, appropriately enough, our observatory is fully powered by starlight – that is to say, a 12 kW rooftop photovoltaic system with 54 kWh battery storage. And our transportation needs are covered by two Kia electric vehicles.

  • As an astronomer and planetary scientist, Carl Sagan was at the forefront in advocating action to prevent the worst effects of climate change. When he died in 1997, former Vice President Al Gore attended the memorial service and delivered the closing eulogy.

    "In reflecting on what he meant to this world, I am in awe of what he accomplished.”

    Picking up the torch to combat global warming, Gore established the Climate Reality Project – a grass roots organization that advocates for change, and to accelerate the transition from fossil fuels.

  • The Pine Gulch Fire near Grand Junction, Colorado. Image via Rawpixel.

What's Next?

Some years back, my daughter and I had the privilege of meeting Al Gore in Los Angeles, and we signed up to become trained and certified Climate Reality trainers. Consequently, if your organization would like a free presentation on this topic, anywhere in world, drop us a line at info@bracken-observatory.com, and we’ll be happy to help set that up for you! Better yet, sign up to become a Climate Reality Leader yourself at https://www.climaterealityproject.org/training.