Introduction

The Hungarian edition opens with four stanzas from Sándor Petőfi's narrative poem János vitéz (John the Valiant, 1844). In them the army climbs mountains so high that it marches close to the Sun and the stars.

Venus is about the size of Earth. Yet it holds far more to map. Its whole surface is dry land, so its land area is much larger than all the continents on Earth. In one way it is like the ocean floor: its surface cannot be seen from space. It can only be mapped by radar.

Venus is like Earth in another way, too. Most of its surface is basaltic lava plains, like the oceanic crust on Earth. It has millions of small volcanic cones and about as many fractures. It is a world shaped mainly by internal forces. Its dense carbon dioxide atmosphere comes from volcanism and drives a strong greenhouse effect. This atmosphere also controls the processes that act on the surface from outside.

In 1961, American, British and Soviet radio telescopes sent pulses towards Venus. From the reflected signal they measured the distance of Venus and its rotation period. At that time, many still thought that the cloudy planet near the Sun was covered by lush rainforests, swamps or deserts. In 1962, the Mariner 2 spacecraft measured the surface temperature. This ended all the earlier ideas.

Today the key questions are these. Was there ever water on Venus? If so, what was the surface like at that time, before the runaway greenhouse effect? Is there clear geological evidence of that era, or of the loss of the water? Such traces might survive in the oldest, rugged terrains called tesserae. There are many open questions about how Venus works, too. Researchers found that craters are scattered at random on the surface. Since then, they have proposed two models of how the surface evolves. In the first, internal heat builds up for a long time. Then it breaks out all at once, with volcanism across the whole planet. In the second, the crust releases its internal heat slowly and steadily, "on a low flame", through local, patchy volcanism. We do not know why coronae, novae and arachnoids are so common on Venus, while they are unknown on Earth. We do not know what material carved the canali. We do not know how the material that appears only on high ground forms. Above all: was there ever life on Venus? And are there still traces of it (for example below the surface), or survivors (for example in the atmosphere)?

In the 1970s, studies of the atmosphere of Venus started the research that led to the discovery of the ozone hole on Earth. The runaway greenhouse effect of Venus, and perhaps its evaporated oceans, help us understand how a greenhouse catastrophe unfolds. Earth may face one, too. Venus also shows that two planets of the same size and similar composition (Earth and Venus) can evolve in very different directions. But what caused the difference?

Our knowledge of Venus has grown much more detailed. Still, we work with radar images taken in the early 1990s. No mapping spacecraft has orbited the planet since then. Only recently, observations by the Japanese Akatsuki and the American Parker probes showed something new. In the infrared, we can see deeper into the thick cloud layer, perhaps even down to the surface.

In the early 2030s, several radar mapping spacecraft will work at Venus. This atlas was made for the new generation of planetary scientists, who may one day work with their data.

About the book

The questions of Venus research: Was there water on Venus? What was its surface like then? Are there traces of that era on the surface today? How does its volcanism work? Was there life on Venus, and are there traces or survivors of it?

So this book does not answer these questions. Perhaps you, the reader, will answer them one day. The book describes the typical landforms of the surface, with images and with the theories of how they formed.

Quite a few of these landforms are unknown on Earth. The glowing hot surface of Venus is not very inviting for people today. Still, Earth's "twin planet", a geologically alien world, can teach us a lot about the past and the distant future of our own planet.

About the printed volume

Edited by

Henrik Hargitai

Series

Planetary Science Library 2

Publisher

Cosmic Materials Space Research Group (KAVÜCS), Budapest, 2023

Language

Hungarian

ISBN

978-963-87767-7-8 (print), 978-963-87767-6-1 (PDF)

DOI

https://doi.org/10.21862/venusz2023

Text and maps

© Henrik Hargitai 2023

Proofreader

Eszter Botos

Printer

Korrekt Nyomdaipari Kft.

Support

Publication was made possible by support from the Hungarian Ministry of Foreign Affairs and Trade, under Government Decision 1953/2021 (XII. 22.).

Radar images

JPL/NASA

Outline of Hungary

The outline on the Radar features page was made with Country Movers (http://countrymovers.elte.hu/), programmed by Mátyás Gede.