Sidereal Day to Month Conversion Calculator: Free Online Tool

Convert sidereal days to months with our free online time converter.

From:

Sidereal Day

To:

Month

How to Use the Calculator:

Enter the value you want to convert in the 'From' field (Sidereal Day).
The converted value in Month will appear automatically in the 'To' field.
Use the dropdown menus to select different units within the Time category.
Click the swap button (⇌) to reverse the conversion direction.

How to Convert Sidereal Day to Month

Converting Sidereal Day to Month involves multiplying the value by a specific conversion factor, as shown in the formula below.

Formula:

1 Sidereal Day = 0.0327652 months

Example Calculation:

Convert 60 sidereal days: 60 × 0.0327652 = 1.965911 months

Disclaimer: For Reference Only

These conversion results are provided for informational purposes only. While we strive for accuracy, we make no guarantees regarding the precision of these results, especially for conversions involving extremely large or small numbers which may be subject to the inherent limitations of standard computer floating-point arithmetic.

Not for professional use. Results should be verified before use in any critical application. View our Terms of Service for more information.

What is a Sidereal Day and a Month?

A sidereal day is the time it takes for the Earth to complete one full rotation on its axis relative to the distant, fixed stars. It is approximately 23 hours, 56 minutes, and 4.091 seconds long. This is slightly shorter than the 24-hour solar day, which is based on the Earth's rotation relative to the Sun.

A month is a unit of time, used with calendars, that is approximately based on the orbital period of the Moon around the Earth. In the Gregorian calendar, a month can have 28, 29, 30, or 31 days. For conversions, an average month is often defined as 1/12th of a year, which is approximately 30.44 days (365.25 days / 12 months).

Note: The Sidereal Day is part of the imperial/US customary system, primarily used in the US, UK, and Canada for everyday measurements. The Month belongs to the imperial/US customary system.

History of the Sidereal Day and Month

The concept of the sidereal day originates from ancient astronomy. Early astronomers observed that the stars appeared to return to the same position in the sky slightly earlier each day when measured against the Sun's cycle. This discrepancy led to the understanding that the Earth's rotation period relative to the background stars (sidereal) was different from its rotation period relative to the Sun (solar). Accurate measurement of the sidereal day became crucial for precise astronomical observations and timekeeping, allowing astronomers to predict the positions of celestial objects.

The concept of the month originated from observing the lunar cycle (the period from one new moon to the next, about 29.5 days). Early calendars, like the Roman calendar, were often lunar or lunisolar. The Gregorian calendar, now used internationally, standardized the month lengths (mostly 30 or 31 days) to align the calendar year more closely with the solar year, largely detaching the calendar month from the strict lunar cycle.

Common Uses for sidereal days and months

Explore the typical applications for both Sidereal Day (imperial/US) and Month (imperial/US) to understand their common contexts.

Common Uses for sidereal days

The sidereal day and sidereal time are primarily used in:

Astronomy: To point telescopes accurately at celestial objects. Astronomical observatories use sidereal clocks to know when specific stars or galaxies will be overhead or in a particular position for observation.
Astrophysics: For calculations involving celestial mechanics and the timing of astronomical events.
Satellite Tracking: Used in calculations for positioning and tracking artificial satellites in Earth orbit.
Geodesy: For precise measurements related to the Earth's rotation and orientation in space.

It is generally not used for civil timekeeping, which relies on the solar day.

Common Uses for months

Calendars: The primary division of the year for dating and scheduling longer-term events.
Billing & Finance: Common cycle for salaries, rent/mortgage payments, subscriptions, bank statements, and financial reporting.
Planning: Used for medium-term planning (monthly goals, project milestones).
Time Measurement: Expressing durations longer than weeks (e.g., project duration, age of infants, gestation periods).
Seasonality: Often associated with seasonal changes, although this varies by month and hemisphere.

Frequently Asked Questions

Questions About Sidereal Day (sidereal day)

How long is a sidereal day in standard time?

A mean sidereal day is approximately 23 hours, 56 minutes, and 4.091 seconds (or about 86,164.091 seconds). This is roughly 3 minutes and 56 seconds shorter than a standard 24-hour solar day.

Why is a sidereal day shorter than a solar day?

A sidereal day measures Earth's rotation relative to distant stars. A solar day measures rotation relative to the Sun. As the Earth rotates, it also orbits the Sun. After one full rotation relative to the stars (one sidereal day), the Earth has moved slightly along its orbit. It needs to rotate a little bit further (about 1 degree, taking nearly 4 minutes) to bring the Sun back to the same apparent position in the sky (completing a solar day).

Is sidereal time the same everywhere on Earth?

No, just like solar time, local sidereal time depends on your longitude. At any given moment, different locations on Earth will have different local sidereal times, corresponding to which part of the celestial sphere is currently crossing their local meridian. However, the duration of a sidereal day is the same everywhere.

About Month (mo)

How many days are in a month?

It varies: 30 days (April, June, September, November), 31 days (January, March, May, July, August, October, December), or 28/29 days (February).

Why do months have different lengths?

The varying lengths are a historical artifact from the Roman calendar adjustments, refined in the Julian and Gregorian calendars, aimed at aligning the calendar year with the solar year while maintaining 12 months.

What is an average month length used for conversions?

For calculations, an average month is often taken as 30.4375 days (365.25 days / 12 months).

Is a month based on the Moon?

Historically, yes. The word "month" is related to "Moon". However, in the Gregorian calendar, the link is approximate; calendar months don't precisely track the lunar phases.

Conversion Table: Sidereal Day to Month

Sidereal Day (sidereal day)	Month (mo)
1	0.033
5	0.164
10	0.328
25	0.819
50	1.638
100	3.277
500	16.383
1,000	32.765

All Time Conversions

Second to Minute Second to Hour Second to Day Second to Week Second to Month Second to Year Second to Millisecond Second to Microsecond Second to Nanosecond Second to Decade Second to Century Second to Millennium Second to Fortnight Second to Planck Time Second to Shake Second to Sidereal Day Second to Sidereal Year Minute to Second Minute to Hour Minute to Day Minute to Week Minute to Month Minute to Year Minute to Millisecond Minute to Microsecond Minute to Nanosecond Minute to Decade Minute to Century Minute to Millennium Minute to Fortnight Minute to Planck Time Minute to Shake Minute to Sidereal Day Minute to Sidereal Year Hour to Second Hour to Minute Hour to Day Hour to Week Hour to Month Hour to Year Hour to Millisecond Hour to Microsecond Hour to Nanosecond Hour to Decade Hour to Century Hour to Millennium Hour to Fortnight Hour to Planck Time Hour to Shake Hour to Sidereal Day Hour to Sidereal Year Day to Second Day to Minute Day to Hour Day to Week Day to Month Day to Year Day to Millisecond Day to Microsecond Day to Nanosecond Day to Decade Day to Century Day to Millennium Day to Fortnight Day to Planck Time Day to Shake Day to Sidereal Day Day to Sidereal Year Week to Second Week to Minute Week to Hour Week to Day Week to Month Week to Year Week to Millisecond Week to Microsecond Week to Nanosecond Week to Decade Week to Century Week to Millennium Week to Fortnight Week to Planck Time Week to Shake Week to Sidereal Day Week to Sidereal Year Month to Second Month to Minute Month to Hour Month to Day Month to Week Month to Year Month to Millisecond Month to Microsecond Month to Nanosecond Month to Decade Month to Century Month to Millennium Month to Fortnight Month to Planck Time Month to Shake Month to Sidereal Day Month to Sidereal Year Year to Second Year to Minute Year to Hour Year to Day Year to Week Year to Month Year to Millisecond Year to Microsecond Year to Nanosecond Year to Decade Year to Century Year to Millennium Year to Fortnight Year to Planck Time Year to Shake Year to Sidereal Day Year to Sidereal Year Millisecond to Second