astronomy Archives - Page 31 of 418 - The Spacewriter's Ramblings

I remember back in the early days of science fiction, writers thought that our sister planet Venus might be a swamp world filled with life. If you’re a Heinlein fan, for example, you might have read “Between Planets”, which took place on a very watery planet populated with aliens, including a Venerian dragon. That was the state of public views of the planet until the Space Age. The public didn’t expect to find anything different, much less surface features such as alien-looking volcanoes on Venus.

That watery depiction of the planet went away when the first spacecraft actually got to Venus in the 1960s. They showed us what scientists had long suspected: that the planet is a cloud-covered desert and a not-very-hospitable place. It’s so hot there that probably nothing can live on the surface. Even if life existed there, the sulfuric acid rain and incredible atmospheric pressure would play havoc with it.

In the 1990s, Magellan gave us high-resolution radar views of the surface. They provided tantalizing visual evidence of volcanoes and other features on the Venerian landscape. But, were those volcanoes still active? Or dormant?

Venus as seen by Magellan spacecraft. Radar scans made by the mission showed areas where lava has flowed in the past from mountains and other vents. Courtesy NASA

Venus Volcanoes: The Debate vs. Data

These and other questions are still being debated. Scientists continue to sift through data from Magellan and other missions to figure out if Venus has live volcanoes. Recent studies show that the volcanoes could still be active. Some flows may only be a few years old. If so, that means Venus is the only other planet in the solar system with active volcanoes. The bigger news is that Venerian activity could give scientists insight into the interiors of the terrestrial planets. We already know something about our own world’s interior and are learning about Mars. But, Venus has remained quite mysterious.

How to figure out if Venus’s volcanoes are still active? Study the flows. In particular, look at their appearance. On Earth, that’s easy. but, Venus is a different proposition. So, a group of scientists from the Universities Space Research Association (USRA), led by Dr. Justin Filiberto of the Lunar and Planetary Institute (LPI), focused on something called the “alteration rate” of fresh lava. That is what happens to lava flows when they get to a planet’s surface.

What Changes Lava

Here on Earth, when lava emerges, it immediately cools. It can get rained on (or flow into ocean), which changes it. The minerals in the lava also can be altered by interactions with the atmosphere. In the field, geologists can tell roughly how old a flow is by how it has been altered after it cools. For example, a fresh pahoehoe flow has a somewhat shiny, crinkly surface. That thin crystalline “overlay” can be shattered by a rainstorm or when someone walks over it (after cooling).

Other changes can “weather” the lava, too, and there’s a distinct difference in appearance between new and older flows. If you study it with various instruments, you can also find other changes. The big question facing the research team was how the flows on Venus would be altered. And, how long would it take for them to change?

Venus and the Altered Flows

Dr. Filiberto’s team used data from the Magellan mission as well as the European Space Agency’s Venus Express orbiter to study Venus lava flows. They looked at infrared light emitted from the surface at night. The resulting data showed them what “fresh” flows looked like on Venus versus older, weathered flows.

The team also constructed an experiment in the lab that mimicked Venus’s corrosive and hot atmosphere, to see what happens to lava flows when they come into contact with it. At least one mineral, called olivine, reacts with such an atmosphere pretty quickly. After a relatively short period of time (a few weeks at most), the olivine gets coated with oxides such as magnetite and hematite. On Venus, such a change would take just a few years.

So, flows on Venus that are rich in olivine that is coated with oxides may to answer the question: when did volcanoes on Venus erupt last? If they’re pretty recent, then it means that Venus has activity volcanoes spewing lava on to its surface. Judging by the visual evidence given by Magellan and other spacecraft, I’d say that’s a foregone conclusion. BUT, in science, we have to nail down everything with facts and data. That’s the value of the USRA study, and it gives new insight into the interior of our “sister” planet Venus.

I know, a lot of science writers and bloggers are publishing their “greatest hits” lists of space and astronomy events this week and next. A lot happened in 2019, some really good while other events were less than wonderful. I think it’s all worth examining. However, an article on that would rapidly take on book-size proportions and, others are doing it for me.

So, instead of inflicting on you MY list of orbital science accomplishments or pretty pictures from observatories, I’m going to talk about something else: our loss of the beautiful night sky. The stars are where we came from, and people have watched and studied them from the earliest times. They are a global heritage we all share.

Those of you who have followed me for a while know that I was involved in the production of a short video for the International Dark-Sky Association. It’s called Losing the Dark. It was originally made for planetarium domes and continues to get used in theaters around the world. We also made a flat-screen version for people to use in lectures and public presentations about light pollution. (You can get more info on the video here. It was produced a few years ago. In the course of six minutes, LTD outlines the challenges that light pollution pose).

A study of the lights at night on Earth made by the European Space Agency. Image of Europe at night by ESA astronaut Alexander Gerst.

Losing the Dark of Night

The image here shows what our planet looks like at night, from space. Lights in many places. I live in a reasonably dark-sky area, but many people do not. The problem is particularly pronounced in big cities. There, people might be able to see planets and a few of the brighter stars, as well as the Moon. So, as the video points out, many people have never seen the Milky Way. Kids grow up not knowing about the beauty of the night sky. Astronomers are, of course, quite sensitive to the loss of darkness. In the video, I coined the phrase, “We are losing the dark of night at the speed of light”. That sentiment is even truer these days than it was when I wrote the script.

So, what do we do? The video outlines simple steps that individuals and communities can take to curtail stray light. We don’t need to use unnecessary lights. When we do have outdoor lights, we should shine them directly where we need them (not up into the sky). And, we should use the correct lighting types for each situation. In more recent times, we use LEDs in streetlights, which saves energy. But, IDA and others have urged communities to use cooler LEDs. The cheapest, garish blue ones do even worse damage to health than the old incandescents did.

Overuse of lighting not only costs a lot of money, but it’s a waste of fossil fuels. We are moving toward more sustainable power sources, which is good. But, that shouldn’t stop us from over-spending on lighting up the night sky.

What Are We Saving?

So, one question I sometimes get when I talk about light pollution is: “Why should we care what astronomers need? Doesn’t everyone’s safety come first?”

Let’s deconstruct that. First, what astronomers need are dark skies to study objects in the sky. Serious science gets done from the ground on Earth, science that enables us to understand our own home as well as the rest of the universe. The nations of planet Earth do fund astronomy research money and provide other forms of support. So, let’s not waste that money and effort by removing the view of objects we’re paying people to study.

Second, lighting does not always equal safety. The IDA has an amazing page about the payoffs for proper lighting and safety. It explains why certain forms of outdoor lighting at night can actually NOT enhance safety and security. Properly lit pathways and buildings DO provide safety without impinging on the night sky. Furthermore, human health isn’t just about safety in dark situations. It also extends to our health. For example, light pollution has been shown to impinge on people’s sleep cycles (and circadian rhythms). Beyond human health, stray light affects the health of other living things on this planet.

Light and Life

A couple of months ago, I gave a presentation of Losing the Dark to a local environmental group. I also learned more about the effects of light pollution on insects and fish from another speaker on our panel. It was pretty eye-opening for me — and I think for many in the audience. It probably shouldn’t be so surprising to all of us that light affects life. All the living things on this planet had their evolutionary cycles controlled by light (or the lack of it). So, when our artificial lights change the conditions in which we all “grew up”, it’s naturally going to affect our life processes.

Use Light Wisely Starting Now

In the end, I know we’re not going to give up artificial light. Nobody’s asking any of us to do that. What I and others who advocate for dark skies to do to use lighting wisely. It’s that simple.

All of us, as well as the plants and animals who share this planet with us, will benefit. So, check out the IDA pages about light pollution. See if there’s something YOU can do to help mitigate light pollution, even in your own home or community. Make it a goal for 2020 and let’s slow the loss of the dark nights across our beautiful planet. We’ll all benefit.

The Spacewriter's Ramblings

Category Archives: astronomy

Active Volcanoes on Venus?