A LIFE IN SCIENCE

John Glenn

· date only

Glenn became the first American to orbit Earth in 1962. His later return to space aboard the shuttle made his life a remarkable bridge between the first crewed orbital flights and a mature space program.

NEXT FEATURED MILESTONE

50,000 days

9 Jun 2058 · approximate

See it in the timeline ↓
A DIFFERENT PERSPECTIVE ON HISTORY

A timeline of unusual anniversaries

More coming up →

A curated selection of 22 mathematical, lunar and symbolic planetary milestones. Future dates are planning estimates, not historical observations.

Date estimate · time unknown
Time milestone

100,000,000 seconds

100,000,000 elapsed seconds from your chosen moment.

Calculation details

100,000,000 elapsed seconds from your chosen moment. Date estimate: the starting time is unknown; local noon is used.

≈ Past
Astronomical estimate · UTC
Lunar milestone · Landmark

100 full moons

The 100th astronomical full moon strictly after your starting moment.

Calculation details

The 100th astronomical full moon strictly after your starting moment. Calculated from the Sun–Moon phase geometry using Meeus’s true-phase algorithm. With no starting time, a moon on your starting date can affect the count; local noon is assumed.

≈ Past
Date estimate · time unknown
Planetary milestone

1 Jupiter year

A symbolic anniversary measured in Jupiter’s longer years.

Calculation details

Approximately 1 mean sidereal orbital period of Jupiter (4,332.589 Earth days each). A symbolic anniversary, not an exact planetary return.

≈ Past
Date estimate · time unknown
Planetary milestone

10 Mars years

A symbolic anniversary measured in Mars’s longer years.

Calculation details

Approximately 10 mean sidereal orbital periods of Mars (686.98 Earth days each). A symbolic anniversary, not an exact planetary return.

≈ Past
Date estimate · time unknown
Calendar milestone

1,000 weeks

A 1,000-week anniversary in UTC.

Calculation details

A 1,000-week anniversary in UTC.

≈ Past
Date estimate · time unknown
Beautiful milestone

7,777 days

A rare repeating-digit day count.

Calculation details

A rare repeating-digit day count. An ordinary day with an extraordinary number.

≈ Past
Date estimate · time unknown
Calendar milestone · Landmark

10,000 days

A 10,000-day anniversary in UTC.

Calculation details

A 10,000-day anniversary in UTC.

≈ Past
Date estimate · time unknown
Planetary milestone

1 Saturn year

A symbolic anniversary measured in Saturn’s longer years.

Calculation details

Approximately 1 mean sidereal orbital period of Saturn (10,759.22 Earth days each). A symbolic anniversary, not an exact planetary return.

≈ Past
Date estimate · time unknown
Time milestone · Landmark

1,000,000,000 seconds

1,000,000,000 elapsed seconds from your chosen moment.

Calculation details

1,000,000,000 elapsed seconds from your chosen moment. Date estimate: the starting time is unknown; local noon is used.

≈ Past
Date estimate · time unknown
Beautiful milestone

12,345 days

A beautifully ordered day count.

Calculation details

A beautifully ordered day count. An ordinary day with an extraordinary number.

≈ Past
Astronomical estimate · UTC
Lunar milestone

500 full moons

The 500th astronomical full moon strictly after your starting moment.

Calculation details

The 500th astronomical full moon strictly after your starting moment. Calculated from the Sun–Moon phase geometry using Meeus’s true-phase algorithm. With no starting time, a moon on your starting date can affect the count; local noon is assumed.

≈ Past
Date estimate · time unknown
Calendar milestone

500 months

A calendar-month anniversary.

Calculation details

A calendar-month anniversary. Shorter months use their last day.

≈ Past
Date estimate · time unknown
Planetary milestone · Landmark

50 trips around the Sun

An approximate trip-count based on Earth’s orbit, not a civil-calendar birthday.

Calculation details

Approximately 50 mean sidereal orbital periods of Earth (365.256 Earth days each). A symbolic anniversary, not an exact planetary return.

≈ Past
Date estimate · time unknown
Calendar milestone · Landmark

20,000 days

A 20,000-day anniversary in UTC.

Calculation details

A 20,000-day anniversary in UTC.

≈ Past
Date estimate · time unknown
Planetary milestone

2 Saturn years

A symbolic anniversary measured in Saturn’s longer years.

Calculation details

Approximately 2 mean sidereal orbital periods of Saturn (10,759.22 Earth days each). A symbolic anniversary, not an exact planetary return.

≈ Past
Date estimate · time unknown
Planetary milestone

5 Jupiter years

A symbolic anniversary measured in Jupiter’s longer years.

Calculation details

Approximately 5 mean sidereal orbital periods of Jupiter (4,332.589 Earth days each). A symbolic anniversary, not an exact planetary return.

≈ Past
Date estimate · time unknown
Beautiful milestone

22,222 days

A rare repeating-digit day count.

Calculation details

A rare repeating-digit day count. An ordinary day with an extraordinary number.

≈ Past
Astronomical estimate · UTC
Lunar milestone · Landmark

1,000 full moons

The 1,000th astronomical full moon strictly after your starting moment.

Calculation details

The 1,000th astronomical full moon strictly after your starting moment. Calculated from the Sun–Moon phase geometry using Meeus’s true-phase algorithm. With no starting time, a moon on your starting date can affect the count; local noon is assumed.

≈ Past
Date estimate · time unknown
Calendar milestone · Landmark

1,000 months

A calendar-month anniversary.

Calculation details

A calendar-month anniversary. Shorter months use their last day.

≈ Past
Date estimate · time unknown
Beautiful milestone

33,333 days

A rare repeating-digit day count.

Calculation details

A rare repeating-digit day count. An ordinary day with an extraordinary number.

≈ Past
Date estimate · time unknown
Planetary milestone · Landmark

100 trips around the Sun

An approximate trip-count based on Earth’s orbit, not a civil-calendar birthday.

Calculation details

Approximately 100 mean sidereal orbital periods of Earth (365.256 Earth days each). A symbolic anniversary, not an exact planetary return.

≈ Past
Date estimate · time unknown
Calendar milestone · Landmark

50,000 days

A 50,000-day anniversary in UTC.

Calculation details

A 50,000-day anniversary in UTC.

≈ Next · Upcoming

Historical references

Sources for the original date and historical context. The unusual anniversaries above are calculated by Starry Moments, not attributed to these sources.

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