Key parameters at a glance

A radius of 4.02 Earth radii
A mass of 5.57 Earth masses
Surface gravity around 0.34 g
An orbital period of 31.784 days
Semi-major axis 0.2138 AU
Equilibrium temperature 752 K (479 °C)
Distance from Earth 3,943.75 light-years
Earth Similarity Index 0.263
Travel time at Voyager 1 speed 69,547,990 years

4 siblings around Kepler-33

Kepler-33 e shares its host star with 4 other confirmed planets. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
Kepler-33 b	Super-Earth	1.74	3.68	5.668	1,336	2011
Kepler-33 c	Sub-Neptune	3.20	0.39	13.176	1,009	2011
Kepler-33 d	Neptune-like	5.35	3.91	21.776	853	2011
Kepler-33 e this	Neptune-like	4.02	5.57	31.784	752	2011
Kepler-33 f	Neptune-like	4.46	9.60	41.029	691	2011

Kepler-33 e Planet Profile

Physical Specs

Radius

4.02 R⊕

Radius (Jupiter)

0.359 R♃

Mass

5.57 M⊕

Mass (Jupiter)

0.018 M♃

Density

0.80 g/cm³

Surface Gravity

0.34 g (Earth)

Classification

Planet Type

Neptune-like

ESI Score 0.263

HZ Position Inner

Controversial No

Discovery

Year 2011

Method Transit

Facility Kepler

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#565of 574

top 98.3%

This planet

4.02R⊕

Neptune-like median

6.39R⊕

Nearest-size peers

K2-360 c 4.02 R⊕ Kepler-590 b 4.02 R⊕ Kepler-359 d 4.01 R⊕

Metric	Earth	Kepler-33 e	Jupiter
Radius (R⊕)	1.00	4.02	11.21
Mass (M⊕)	1.00	5.57	317.83
Density (g/cm³)	5.51	0.80	1.33
Surface Gravity (g)	1.00	0.34	2.53
Insolation (S⊕)	1.00	74.72	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	5.570 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 158935283

Gaia DR2

Gaia DR2 2127355923723254272

Gaia DR3

Gaia DR3 2127355923723254272

System

Kepler-33

Percentile among Neptune-like cohort

Radius 4.020 R⊕ · percentile 1 / cohort 574

Mass 5.570 M⊕ · percentile 1 / cohort 574

Orbital period 31.78 d · percentile 61 / cohort 524

Distance 1,209.16 pc · percentile 79 / cohort 572

ESI 0.263 · percentile 41 / cohort 574

Orbit & Habitability

Orbital Dynamics

Period

31.784 days

Semi-major axis

0.2138 AU

Eccentricity

0.000

Inclination

88.94 °

Year Length

A year here lasts approximately 31.78 Earth days (8.7% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.2138 AU.

Transit Fingerprint

Depth

0.047 %

Duration

8.900 h

Impact parameter b

0.470

Rp / R★

0.020110

Transit midpoint (BJD)

2,454,968.8715

Photometric dip

Transit produces a flux drop of 467 ppm lasting ≈ 8.90 h.

Extended Orbital Architecture

Planet / star radius ratio

0.020110

Semi-major axis / stellar radius

24.900

Impact parameter (b)

0.470

Transit mid-time (BJD)

2,454,968.8715

Angular separation (arcsec)

0.17700

Eq. Temperature

752K

(479 °C)

Insolation (S⊕)

74.72

Earth = 1.00

Earth Similarity (ESI)

0.263

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water.

Detection Signatures

Transit photometry

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

Transit timing variations

Gravitational interactions from neighbours have been detected.

Discovery Paper

Primary reference

Lissauer et al. 2012

Instrument

Kepler CCD Array

Publication

2012-05

Observation locale

Space

Discovery cohort

Planets confirmed in 2011 at Kepler (12 shown).

Kepler-22 b · Sub-Neptune Kepler-20 d · Sub-Neptune Kepler-26 c · Sub-Neptune Kepler-19 c · Sub-Neptune Kepler-26 b · Sub-Neptune Kepler-28 c · Super-Earth Kepler-10 c · Sub-Neptune Kepler-20 f · Rocky Terrestrial Kepler-42 d · Rocky Terrestrial Kepler-16 b · Neptune-like Kepler-28 b · Super-Earth Kepler-34 b · Neptune-like

Host System: Kepler-33

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,904 K — hotter than the Sun (5,778 K)

Estimated Age

4.27 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

1.820 R☉

Stellar Mass

1.291 M☉

Metallicity [Fe/H]

0.03

Extended Stellar Properties

Surface gravity (log g)

4.027 dex

Stellar density

0.300 g/cm³

Systemic radial velocity

14.09 km/s

Rotational v·sin i

3.40 km/s

Metallicity ratio

[Fe/H]

Distance

1,209.16 parsec

Light-years 3,943.75 ly

V-band magnitude

14.10 mag

Voyager-speed travel 69,547,990 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

0.798 mas

Total Proper Motion

13.130 mas/yr

PM Right Ascension

-1.11 mas/yr

PM Declination

-13.08 mas/yr

Galactic Cartesian (pc)

x = 0.227 · y = -0.656 · z = 0.719

Equatorial (J2000)

RA 289.07753° · Dec 46.00517°

Galactic ℓ, b

77.263° · 15.134°

Ecliptic λ, β

305.681° · 67.096°

HTM-20 index

1983176106