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Table 2.

Different environments in the Solar System and their characteristics related to planetary space weather. In order to characterize the effects of solar emissions and winds on different bodies, we consider the existence of ionosphere (I), magnetosphere (M), exosphere (E). The interplanetary (or planetary) magnetic field inclination, given in the Table’s last column, is measured with respect to the body’s spin axis; the estimations of the IMF inclination are based on the Parker model, for an average solar wind velocity equal to 450 km/s.

Planets
Solar system body Distance from the Sun (in AU) Body’s radius (in km) Rotation period (in hours) Planetary space weather regions Atmosphere major composition Magnetic field morphology Solar wind density (in cm−3) Interplanetary magnetic field
Intensity (nT) Inclination (in deg)
Neptune 30.071 24,7641 16.111 I, M, E H2, He, CH4 1 Dipole 0.00815 0.1122 88.1
Uranus 191 25,5591 17.241 I, M, E H2, He, CH4 1 Multipole 0.0215 0.2223 87.0
Saturn 9.51 60,3301 10.6561 I, M, E H2, He1 Dipole 0.115 0.2–0.824 83.9
Jupiter 5.21 71,3981 9.9251 I, M, E H2, He1 Dipole 0.315 0.5–1.2125 79.0
Mars 1.5241 3,3901 24.6231 I, E CO2, N2 1 Crustal fields 3.515 2–326 56.4
Venus 0.7231 6,0511 5,832.61 I, E CO2, N2 1 Induced 1615 1227 35.5
Mercury 0.31–0.471 2,4391 1,407.61 M, E Exosphere: Na, K, Mg, Ca, H, He, Al1 Dipole 32–7316 15–3028 21.1

Satellites
Solar system body Distance from the parent planet (in planet radii) Body’s radius (in km) Rotation period (in Earth days) Planetary space weather regions Major composition of the neutral environment Magnetic field morphology Magnetospheric plasma density (in cm−3) Planet’s magnetic field at the satellite’s distance
Direction and intensity (nT) Inclination

Jupiter's satellites Io 5.912 1,821.62 S 1.772 E Exosphere: SO2 4 1,920 (ions) 2,500 (electrons)17 −1,90029 32 , 33
Europa 9.402 1,560.82 S 3.552 E Exosphere: O2, H2O gas plume5 Induced12 8.8–40.6 (S2+) 5–23.2 (O2+) 7.6–34.8 (H+) 63 –290 (electrons)18 −42029 32 , 33
Ganymede 14.972 2,631.22 S 7.152 M, E Exosphere: O2, H6 Intrinsic dipole and induced13 1–8 (ions) 1–10 (electrons)17 −9029 32 , 33
Callisto 26.332 2,410.12 S 16.692 E Exosphere: CO2, O2 7 Induced12 0.10 (ions) 0.15 (electrons)17 −3029 32 , 33
Saturn's satellites Enceladus 3.953 257 × 251 × 2483 S 1.373 E Exosphere (gas plume): H2O, CO2, Mass 28 (CO or N2), CH4 8 ?14 40 (electrons) 4–40 (ions)19 −37030 32 , 34
Dione 6.263 563 × 561 × 5603 S 2.743 E Exosphere: O2, CO2 9 ?14 13 (electrons) 2–20 (ions)19 −7530 32 , 34
Rhea 8.743 765 × 763 × 7623 S 4.523 E Exosphere: CO2, O2 10 ?14 2 (electrons) 0.4–3 (ions)19 −2530 32 , 34
Titan 20.273 2,5753 S 15.953 I, E Atmosphere: N2, CH4 11 Induced14 30–1,000 (electrons)20 20–2,000 (ions)21 −5.131 32 , 34
1

As reported in NASA Planetary Fact Sheet http://nssdc.gsfc.nasa.gov/planetary/factsheet/

2

From the NASA Jovian Satellite Fact Sheet http://nssdc.gsfc.nasa.gov/planetary/factsheet/joviansatfact.html; Note that S stands for synchronous rotation.

3

From the NASA Saturnian Satellite Fact Sheet http://nssdc.gsfc.nasa.gov/planetary/factsheet/saturniansatfact.html; Note that S stands for synchronous rotation.

4

As reported in Lopes & Williams (2005).

5

For observations interpreted as indicative for an O2 atmosphere see Hall et al. (1995, 1998), Saur et al. (2011) and McGrath et al. (2004). Observations interpreted as indicative for a transient water plume were discussed in Roth et al. (2014a).

6

See Hall et al. (1998), Feldman et al. (2000), Barth et al. (1997).

12

For Europa see Khurana et al. (1998, 2009). For Callisto see Khurana et al. (1998).

14

It is currently not known if induced magnetic fields are generated at the inner Saturnian moons. Titan’s ionosphere, being subject to direct erosion by the incident plasma flow, generates an induced magnetosphere around the moon: the ambient magnetospheric field drapes around Titan’ s ionosphere, leading to the formation of a magnetic pile-up region at the ramside and a bipolar magnetotail in the wake region (see Simon et al. 2013b for details).

15

As reported in Richardson et al. (2004).

16

As reported in Milillo et al. (2005).

17

As reported in Kivelson et al. (2004, Table 21.1).

18

For a detailed description of the plasma environment at Europa see Bagenal et al. (2015) and Delamere et al. (2005).

24

See Jackman et al. (2004). These values were measured by Cassini in 2004 and correspond to magnetopause crossings.

25

Ulysses data (1992, 1998, 2004) and Cassini data (2000) taken from Table 1 in Nichols et al. (2006).

26

Estimation based on the analysis of Mars Global Surveyor (MGS) Magnetometer (MAG) data from the region upstream from Mars (Brain et al. 2003). The spiral angle was found in the range 32°–70°.

28

See Figure 5 in Baker et al. (2013). CME passages (with stronger magnetic fields in and draped around the CMEs) and other transient solar wind can result in IMF enhancements (Baker et al. 2013).

29

Since neither the orbits nor the spin axes of the moons are significantly inclined to the parent planet’s equatorial plane, we present here the averages around the moon’s orbit as reported in Kivelson & Bagenal (2007). The minus sign indicates that the average field over a planetary rotation period is southward oriented, i.e. antiparallel to the planet’s rotation axis.

32

The magnetic fields of Jupiter and Saturn at the orbits of their moons oscillate in intensity and direction at the giant planets rotation periods, equal to 9.925 h and 10.656 h, respectively.

33

The average field over a planetary rotation period is southward oriented, i.e. antiparallel to Jupiter’s axis of rotation (Kivelson & Bagenal 2007). The spin axes of the moons are not significantly inclined to the parent planet’s equatorial plane: 0.04° (Io); 0.47° (Europa); 0.21° (Ganymede); 0.51° (Callisto), according to http://nssdc.gsfc.nasa.gov/planetary/factsheet/joviansatfact.html. Therefore the inclination of the parent planet’s magnetic field (with respect to the satellite’s spin axis) is negligible.

34

As in the Jupiter’s case, the spin axes of the moons are not significantly inclined to the parent planet’s equatorial plane: 0.00° (Enceladus); 0.02° (Dione); 0.35° (Rhea); 0.33° (Titan), according to http://nssdc.gsfc.nasa.gov/planetary/factsheet/saturniansatfact.html. Therefore the inclination of the parent planet’s magnetic field (with respect to the satellite’s spin axis) is negligible.

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