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23 votes

Are there any planets or moons denser than Earth?

I feel it's a cheap answer but heavy Jupiters can get much denser than Earth because planets with Jupiter's mass stop adding size as they add more mass. A planet with Jupiter's size and 10-12 times ...
userLTK's user avatar
  • 24.1k
15 votes
Accepted

How many iridium layers do we know, besides the K-Pg one (the dinosaur killer "smoking gun")?

There are other iridium anomalies, particularly the Devonian-Carboniferous boundary (D-C boundary), about 350 Ma ago. The K-Pg boundary is only 66 Ma old. Just because there is an iridium anomaly ...
Fred's user avatar
  • 2,169
14 votes
Accepted

When was the last volcanic eruption on Mars?

Berman and Hartman (2002) dated some lava flows of the Athabasca–Marte Valles system at < 20 Ma (mega-annum). Later, Vaucher et al. (2009) dated lava flows of the same region, finding ages even ...
Jean-Marie Prival's user avatar
10 votes
Accepted

What is the temperature 55 km beneath the surface of Mars?

If we look at Mars' possible geothermal gradient (see Earth's) which is about 25 °C per km. Using the low estimate of Mars's gradient to be 1/4 that of Earth's Source, that's a bit over 6° C per km. ...
userLTK's user avatar
  • 24.1k
10 votes
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Is there convection in Mars' mantle?

There are several ways to look at this. One rather simple way is to compute the Rayleigh number of Mars' mantle. The Rayleigh number is a dimensionless number defined as: $Ra = \dfrac{\rho g \alpha \...
Jean-Marie Prival's user avatar
9 votes
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Why is the Moon smooth near the equator and bumpy near the poles?

There are a few factors that create this effect: First in the visual light images, the view around the equator is seen back lit, with almost no shadow, the few around the pole is seen with low ...
James K's user avatar
  • 123k
9 votes
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Are there any planets or moons denser than Earth?

From the Wikipedia page on Chthonian planet: Transit-timing variation measurements indicate for example that Kepler-52b, Kepler-52c and Kepler-57b have maximum-masses between 30 and 100 times the ...
sno's user avatar
  • 1,456
8 votes

Caves traced in nine planets of solar system

A key requirement for caves is solid substance: while there may be rock cores inside the giant planets, the rest is liquid or gas. Metallic hydrogen may be solid or liquid in Jupiter, but presumably ...
Anders Sandberg's user avatar
8 votes
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If an earthquake happens on Mars, is it still an earthquake?

As pointed out in the comments, some do prefer to use different terms for quakes on other bodies, and you can see here that "marsquake" does have scholarly usage. That said, there is also scholarly ...
called2voyage's user avatar
  • 6,322
7 votes
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Appearance of sun at geologic past

I'm doing some palaeobiology-landscape rendering; so I'm thinking if I want to add the sun in such pictures; should I draw it just like present day ? Although the Sun was less luminous 4.5 billion ...
StephenG - Help Ukraine's user avatar
7 votes
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What are the effects of mass concentration along a planet's axis of rotation?

Does this mean that Mars' center of mass is slightly shifted to the south? Yes, by about 3 kilometers, and it is also shifted by about 1.5 km along the y axis in the direction of Tharsis. See Table 4 ...
Jean-Marie Prival's user avatar
6 votes

How many quakes have been detected by InSight?

This is the latest catalogue from seismic events recorded by InSight: Mars Seismic Catalogue, InSight Mission; V5 2021-01-04. This report includes seismic events up to October 12, 2020. These ...
Wilhelmroentgen's user avatar
6 votes
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How did the Archimedes crater fill with lava?

Great question! The mare lava bubbled up through fractures in the floor of the crater, burying its ring system and central peak.
AstroShannon's user avatar
6 votes
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Could Mars have oil?

Planet solidifying. No molten core iron -> no magnetosphere -> solar wind strips atmosphere. Without atmosphere to cycle in exposed water also leaves. Why did Mars freeze solid & Earth has not (...
tomc's user avatar
  • 463
6 votes
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How massive must a rocky body be to liquify adequately to eliminate internal mass concentrations that could disrupt natural satellite orbits?

Planets and moons are never going to be completely homogenized such that their radial density is perfectly spherically symmetric. They're always going to have mass concentrations (mascons) with ...
zephyr's user avatar
  • 15k
6 votes

What discoveries were made thanks to Pioneer orbiter data?

The NASA Pioneer Venus Orbiter mission was planned for a minimum duration of 243 days to cover all Venus longitudes, but eventually sent data for about 14 years. Some of the major results are: The ...
Ritesh Singh's user avatar
6 votes

Why don't scientists believe Earth's surface water came up from the mantle?

If the question is actually "why don't any geologists believe that Earth's surface and near-surface waters were brought up from the Earth's interior?", then the premise is false since many ...
David Bailey's user avatar
5 votes

How much mass do the volcanoes of Io erupt past escape velocity?

The velocity required to escape the gravitational attraction of a massive body is given by the following equation: $$ v_{\mathrm{escape}} = \sqrt{\frac{2GM}{R}}$$ where $G$ is the gravitational ...
christopherlovell's user avatar
4 votes

Appearance of sun at geologic past

You can divide this into two astronomical epochs, which are most easily understood in terms of the Hertzsprung-Russell diagram. The first is the pre-main-sequence (PMS) phase, where the protosun ...
ProfRob's user avatar
  • 153k
4 votes

Was the young Sun cooler or hotter than it is today?

The temperature at a given distance from the Sun depends on the Sun's luminosity, not on its temperature. The following graph plots a series of tracks for how the luminosity versus temperature evolves ...
ProfRob's user avatar
  • 153k
4 votes

How did the mountain range form in Galle crater?

Rapidly! Galle is a large (230km) crater. In the processes that occur in the aftermath of a massive impact, deep rocks can be pushed up. Often this creates a central peak, but it can also form a ring ...
James K's user avatar
  • 123k
4 votes

In which Indian Institutions can I find Planetary Scientists or Planetary Geologists?

There are probably many, but I'll highlight one. The Physical Research Laboratory has a Planetary Research Division. We study solar system objects, their atmospheres, surfaces and interiors, and ...
James K's user avatar
  • 123k
4 votes
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Geological/tectonic/thermal/etc. implications of Rayleigh numbers ≥ 100,000,000

(This is more an answer to this part: "If any of these are physically impossible, let me know".) As you mention volcanism, plate tectonics, mountains... I make the assumption that you ...
Jean-Marie Prival's user avatar
4 votes

Is an earth-sized moon orbiting a super-earth feasible?

This is an answer only to the second part of your question. If such an enormous moon somehow gets formed or captured, its tidal interaction with its host planet will follow the regular laws. If the ...
Michael_1812's user avatar
  • 1,456
3 votes

Why do rocks on other solar system bodies that have an atmosphere seem to be flat?

I don't know what you're talking about. The only one that seems to have mostly flat rocks is Venus. At least based on what little photographs we have from the surface of Venus. Mars Venus
Katie Katie's user avatar
3 votes
Accepted

Io: Why so much sulfur?

Io is not dominated by sulfur. Io is mostly silicate rock and iron. Sulfur is a thin coating on the surface and sulfur dioxide makes up most of the atmosphere, but that's because sulfur dioxide is a ...
DanielC's user avatar
  • 132
3 votes

Is there a general term used to identify the high flat features within Noctis Labyrinthus on Mars?

The geological term mesa has been used to describe these structures. A transitional zone on Mars, known as the fretted terrain, lies between highly cratered highlands and less cratered lowlands. ...
Fred's user avatar
  • 2,169
3 votes
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Why did the edge of Olympus Mons collapse?

This source from NASA says: Most scientists think the the cliffs formed by landslides. This collapse is driven by the weight of the huge volcano exceeding the strength of the rocks it is built of. ...
IronEagle's user avatar
  • 641

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