Planetary system · 4 known planets · Dorado

TOI-700

Its star: not above the horizon after darkNever rises from London

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Where is TOI-700?

Times for LondonChange city

Below the horizon from London all the time in Dorado.

Rises: Never
Highest: —
Sets: —
Best after dark: —

Can I see TOI-700?

No. The planets of TOI-700 can’t be seen with the eye, binoculars or any amateur telescope: they are lost in their star’s light. What you can do is point toward the star.

The star TOI-700 never rises from London: it is too far south in the sky for this latitude.

Why is TOI-700 interesting?

TOI-700 has 4 known planets, discovered between 2020 and 2023 by the primary transit method.

3 of them are close to Earth’s size or mass, based on the catalog values.

What can you see?

Eyes

Direction only

Not visible.

Binoculars

Not visible.

Telescope

The star is around magnitude 13 and needs a telescope of about 200 mm and a detailed chart. The planets themselves can’t be seen with any backyard telescope.

What you’re likely to see, not what a space telescope photographs.

About

TOI-700 is a red dwarf star about 100 light-years away in the southern constellation Dorado. It has four known planets.

In 2020, NASA’s TESS mission found TOI-700 d, the mission’s first Earth-sized planet in a habitable zone. In 2023 a second Earth-sized planet, TOI-700 e, was found nearby, also within the range where liquid water might be possible.

The star is relatively quiet for a red dwarf, with few strong flares, which makes its planets interesting for future study.

TOI-700 has around 40% of the Sun’s mass. TESS, launched in 2018, surveys most of the sky looking for planets passing in front of nearby bright stars.

TOI-700 d is close to Earth’s size and receives a little less energy from its star than Earth gets from the Sun. TOI-700 e is slightly smaller than Earth.

Because it lies far south, TOI-700 is best placed for observers in the Southern Hemisphere, where Dorado is high on summer evenings.

The TOI-700 system

Known planets of TOI-700 (catalog values from exoplanet.eu)
Planet	Mass	Radius	Orbit	From star	Found	Method
TOI-700 b	1.30 M⊕	0.91 R⊕	9.98 days	0.0677 AU	2020	Primary Transit
TOI-700 c	2.51 M⊕	2.60 R⊕	16.1 days	0.0929 AU	2020	Primary Transit
TOI-700 e	—	0.95 R⊕	27.8 days	0.134 AU	2023	Primary Transit
TOI-700 d	2.42 M⊕	1.07 R⊕	37.4 days	0.1633 AU	2020	Primary Transit

M⊕ / R⊕ = Earth masses / radii; M♃ / R♃ = Jupiter. Masses from radial velocity are often minimum masses. Data: The Extrasolar Planets Encyclopaedia, exoplanet.eu (CC BY 4.0).

Questions

Can I see TOI-700 d?

No. It was found from the tiny dimming of its star as it passed in front.

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Sources: The Extrasolar Planets Encyclopaedia (CC BY 4.0); star chart: Wikidata (CC0). Positions computed for your place and time with astronomy-engine. Data & Licences