Key parameters at a glance

A radius of 12.67 Earth radii
A mass of 807.29 Earth masses
Surface gravity around 5.03 g
An orbital period of 8.159 days
Semi-major axis 0.0801 AU
Equilibrium temperature 1,059 K (786 °C)
Distance from Earth 293.41 light-years
Earth Similarity Index 0.152
Travel time at Voyager 1 speed 5,174,318 years

1 sibling around WASP-8

WASP-8 b shares its host star with 1 other confirmed planet. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
WASP-8 b this	Gas Giant	12.67	807.29	8.159	1,059	2010
WASP-8 c	Gas Giant	12.50	3,003.37	4,323.000	—	2013

WASP-8 b Planet Profile

Physical Specs

Radius

12.67 R⊕

Radius (Jupiter)

1.130 R♃

Mass

807.29 M⊕

Mass (Jupiter)

2.540 M♃

Density

2.10 g/cm³

Surface Gravity

5.03 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.152

HZ Position Inner

Controversial No

Discovery

Year 2010

Method Transit

Facility SuperWASP

Telescope Canon 200mm f/1.8L

Size rank in cohort

Rank by radius

#1170of 1771

top 66.0%

This planet

12.67R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

HATS-50 b 12.67 R⊕ HD 189733 b 12.67 R⊕ TrES-1 b 12.67 R⊕

Metric	Earth	WASP-8 b	Jupiter
Radius (R⊕)	1.00	12.67	11.21
Mass (M⊕)	1.00	807.29	317.83
Density (g/cm³)	5.51	2.10	1.33
Surface Gravity (g)	1.00	5.03	2.53
Insolation (S⊕)	1.00	209.12	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	807.288 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 183532609

Gaia DR2

Gaia DR2 2312679845530628096

Gaia DR3

Gaia DR3 2312679845530628096

System

WASP-8

Percentile among Gas Giant cohort

Radius 12.666 R⊕ · percentile 34 / cohort 1771

Mass 807.288 M⊕ · percentile 62 / cohort 1747

Orbital period 8.16 d · percentile 42 / cohort 1533

Distance 89.96 pc · percentile 33 / cohort 1759

ESI 0.152 · percentile 37 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period

8.159 days

Semi-major axis

0.0801 AU

Eccentricity

0.310

Inclination

88.55 °

Year Length

A year here lasts approximately 8.16 Earth days (2.2% of a terrestrial year) on a highly eccentric trajectory at a mean orbital distance of 0.0801 AU.

Transit Fingerprint

Depth

1.300 %

Duration

4.397 h

Impact parameter b

0.470

Rp / R★

0.116850

Transit midpoint (BJD)

2,458,301.8095

Photometric dip

Transit produces a flux drop of 13,000 ppm lasting ≈ 4.40 h.

Extended Orbital Architecture

Planet / star radius ratio

0.116850

Semi-major axis / stellar radius

18.280

Impact parameter (b)

0.470

RV semi-amplitude (K)

222.200 m/s

Transit mid-time (BJD)

2,458,301.8095

Long. of periastron (ω)

274.22°

Sky-projected obliquity (λ)

-143.00°

Angular separation (arcsec)

0.89000

Eq. Temperature

1,059K

(786 °C)

Insolation (S⊕)

209.12

Earth = 1.00

Earth Similarity (ESI)

0.152

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

Queloz et al. 2010

Instrument

iKon-L CCD Camera

Publication

2010-07

Observation locale

Ground

Discovery cohort

Planets confirmed in 2010 at SuperWASP (12 shown).

WASP-29 b · Neptune-like WASP-23 b · Gas Giant WASP-38 b · Gas Giant WASP-37 b · Gas Giant WASP-32 b · Gas Giant WASP-25 b · Gas Giant WASP-34 b · Gas Giant WASP-21 b · Gas Giant WASP-22 b · Gas Giant WASP-26 b · Gas Giant WASP-24 b · Gas Giant WASP-31 b · Gas Giant

Host System: WASP-8

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,600 K — cooler than the Sun (5,778 K)

Estimated Age

3.00 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

1.030 R☉

Stellar Mass

1.340 M☉

Metallicity [Fe/H]

0.17

Extended Stellar Properties

Surface gravity (log g)

4.500 dex

Stellar density

1.740 g/cm³

Systemic radial velocity

-1.50 km/s

Rotational v·sin i

1.90 km/s

Metallicity ratio

[Fe/H]

Distance

89.96 parsec

Light-years 293.41 ly

V-band magnitude

9.79 mag

Voyager-speed travel 5,174,318 yr

Multi-band Host Photometry — 11 bands

Astrometric Data

Parallax

11.087 mas

Total Proper Motion

110.011 mas/yr

PM Right Ascension

109.75 mas/yr

PM Declination

7.61 mas/yr

Galactic Cartesian (pc)

x = 0.819 · y = -0.001 · z = -0.574

Equatorial (J2000)

RA 359.90087° · Dec -35.03133°

Galactic ℓ, b

354.251° · -76.395°

Ecliptic λ, β

344.331° · -31.742°

HTM-20 index

137568729

Observation Record

Photometric series

Emission spectra

Archive notes