Key parameters at a glance

A radius of 7.06 Earth radii
A mass of 32.10 Earth masses
Surface gravity around 0.64 g
An orbital period of 5.444 days
Semi-major axis 0.0641 AU
Equilibrium temperature 1,270 K (997 °C)
Distance from Earth 372.38 light-years
Earth Similarity Index 0.119
Travel time at Voyager 1 speed 6,566,958 years

WASP-166 b Planet Profile

Physical Specs

Radius

7.06 R⊕

Radius (Jupiter)

0.630 R♃

Mass

32.10 M⊕

Mass (Jupiter)

0.101 M♃

Density

0.54 g/cm³

Surface Gravity

0.64 g (Earth)

Classification

Planet Type

Neptune-like

ESI Score 0.119

HZ Position Inner

Controversial No

Discovery

Year 2019

Method Transit

Facility WASP-South

Telescope Canon 200mm f/1.8L

Size rank in cohort

Rank by radius

#197of 574

top 34.1%

This planet

7.06R⊕

Neptune-like median

6.39R⊕

Nearest-size peers

HAT-P-26 b 7.06 R⊕ Kepler-1519 b 7.06 R⊕ KMT-2023-BLG-0469L b 7.04 R⊕

Metric	Earth	WASP-166 b	Jupiter
Radius (R⊕)	1.00	7.06	11.21
Mass (M⊕)	1.00	32.10	317.83
Density (g/cm³)	5.51	0.54	1.33
Surface Gravity (g)	1.00	0.64	2.53
Insolation (S⊕)	1.00	440.00	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	32.101 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 408310006

Gaia DR2

Gaia DR2 5664957444179338240

Gaia DR3

Gaia DR3 5664957444179338240

System

WASP-166

Percentile among Neptune-like cohort

Radius 7.062 R⊕ · percentile 66 / cohort 574

Mass 32.101 M⊕ · percentile 54 / cohort 574

Orbital period 5.44 d · percentile 22 / cohort 524

Distance 114.17 pc · percentile 26 / cohort 572

ESI 0.119 · percentile 5 / cohort 574

Orbit & Habitability

Orbital Dynamics

Period

5.444 days

Semi-major axis

0.0641 AU

Eccentricity

0.000

Inclination

88.00 °

Year Length

A year here lasts approximately 5.44 Earth days (1.5% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0641 AU.

Transit Fingerprint

Depth

0.281 %

Duration

3.600 h

Impact parameter b

0.390

Rp / R★

0.053010

Transit midpoint (BJD)

2,457,664.3289

Photometric dip

Transit produces a flux drop of 2,810 ppm lasting ≈ 3.60 h.

Extended Orbital Architecture

Planet / star radius ratio

0.053010

Semi-major axis / stellar radius

11.300

Impact parameter (b)

0.390

RV semi-amplitude (K)

10.400 m/s

Transit mid-time (BJD)

2,457,664.3289

Sky-projected obliquity (λ)

3.00°

True obliquity (ψ)

56.20°

Angular separation (arcsec)

0.56100

Eq. Temperature

1,270K

(997 °C)

Insolation (S⊕)

440.00

Earth = 1.00

Earth Similarity (ESI)

0.119

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the dayside is scorched.

Detection Signatures

Transit photometry

A transit dip has been observed from at least one telescope.

Radial velocity

Stellar wobble has been measured spectroscopically.

Discovery Paper

Primary reference

Hellier et al. 2019

Instrument

iKon-L CCD Camera

Publication

2019-09

Observation locale

Ground

Discovery cohort

Planets confirmed in 2019 at WASP-South (9 shown).

WASP-185 b · Gas Giant WASP-171 b · Gas Giant WASP-190 b · Gas Giant WASP-192 b · Gas Giant WASP-182 b · Neptune-like WASP-175 b · Gas Giant WASP-184 b · Gas Giant WASP-169 b · Gas Giant WASP-178 b · Gas Giant

Host System: WASP-166

Spectral Class

F-type yellow-white

Effective Temperature

6,050 K — hotter than the Sun (5,778 K)

Estimated Age

2.10 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

1.220 R☉

Stellar Mass

1.190 M☉

Metallicity [Fe/H]

0.19

Extended Stellar Properties

Surface gravity (log g)

4.340 dex

Stellar density

0.920 g/cm³

Systemic radial velocity

23.63 km/s

Rotational v·sin i

5.10 km/s

Rotation period

12.10 days

Metallicity ratio

[Fe/H]

Distance

114.17 parsec

Light-years 372.38 ly

V-band magnitude

9.35 mag

Voyager-speed travel 6,566,958 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

8.730 mas

Total Proper Motion

56.156 mas/yr

PM Right Ascension

-55.08 mas/yr

PM Declination

10.93 mas/yr

Galactic Cartesian (pc)

x = -0.764 · y = 0.537 · z = -0.358

Equatorial (J2000)

RA 144.87510° · Dec -20.98242°

Galactic ℓ, b

253.962° · 23.136°

Ecliptic λ, β

155.346° · -32.835°

HTM-20 index

-869756272