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Solar System

111 cards · 🇺🇸 English

Planets, dwarf planets, moons, asteroids and comets.

astronomysolar-system

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Solar System

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1Solar System
The gravitationally bound system of the Sun and all objects that orbit it, including eight planets
2How old is the Solar System?
At least 4.568 billion years old
3How did the Solar System form?
From the gravitational collapse of a region within a large molecular cloud, creating the Sun and a protoplanetary disc
4What percentage of the Solar System's mass is the Sun?
99.86% of the system's total mass
5Four terrestrial planets in order from the Sun
Mercury, Venus, Earth, and Mars
6Four outer planets in order from the Sun
Jupiter, Saturn, Uranus, and Neptune
7Which two planets are gas giants?
Jupiter and Saturn
8Which two planets are ice giants?
Uranus and Neptune
9Which planets orbit within the Sun's habitable zone?
Earth and Mars
10What percentage of the non-stellar mass do Jupiter and Saturn possess?
Nearly 90% of the non-stellar mass of the Solar System
11Five officially recognized dwarf planets
Ceres, Pluto, Eris, Makemake, and Haumea (listed by the IAU's Minor Planet Center)
12What four additional Solar System objects are generally identified as dwarf planets?
Orcus, Quaoar, Gonggong, and Sedna
13How many known natural satellites are in the Solar System?
758 known natural satellites
14Two largest moons in the Solar System
Ganymede (of Jupiter) and Titan (of Saturn), both larger than Mercury
15How many known minor planets are in the Solar System?
1,462,402 known minor planets
16How many known comets are in the Solar System?
4,629 known comets
17Frost line
The boundary at approximately 5 AU where material is cool enough for volatile icy compounds to remain solid
18Where is the heliopause detected?
At around 120 AU from the Sun, where the solar wind is halted by the interstellar medium
19Oort cloud
The theorized outermost region of the Solar System beyond 2,000 AU, the source for long-period comets, stretching to the edge of the Hill sphere
20Closest star to the Solar System
Proxima Centauri, at 4.2465 light-years (269,000 AU) away
21Solar System's location in the Milky Way
In the Orion-Cygnus Arm, within the Local Bubble, 24,000-28,000 light-years from the Galactic Center
22How fast does the Solar System orbit the galaxy?
720,000 km/h (450,000 mi/h)
23How long is the Solar System's orbital period around the galaxy?
Approximately 230 million years
24Protoplanetary disc
A rotating disc of dense gas and dust surrounding a newly formed star from which planets form
25Pre-solar nebula
The molecular cloud that collapsed to form the Solar System, consisting mostly of hydrogen, with some helium and small amounts of heavier elements
26How did conservation of angular momentum affect the forming Solar System?
It caused the collapsing cloud to rotate faster and flatten into a protoplanetary disc with a diameter of roughly 200 AU
27How did planets form?
By accretion from the protoplanetary disc, where dust and gas gravitationally attracted each other, coalescing to form ever larger bodies
28Soot line
The boundary where accretion heat exceeded the boiling point of hydrocarbon molecules, leading to low carbon content for inner planets
29Why couldn't terrestrial planets grow very large?
Because refractory materials (metals and silicates) only comprised a small fraction of the solar nebula
30Why could giant planets grow so massive?
Ices beyond the frost line were more plentiful than metals and silicates, allowing them to capture large atmospheres of hydrogen and helium