# How Long Does it Take to Get to The Sun?

Last Updated: August 6, 2024

When we consider other astronomical objects in our solar system, it’s hard to forget the Sun, that massive ball of gas that keeps us from spinning into empty space and lights our day as the familiar yellow/ white ball that could be covered with your thumb. But, how long would it take to get there? Let’s dive into the various factors to determine how long it would take to travel to the Sun!

When calculating travel time you use two basic measurements: the distance and the speed of the vehicle. The average distance from Earth to the Sun — called an astronomical unit or AU— is 92,955,807 miles (149,597,870 kilometers).

However, just as it is here on Earth, travel time highly depends on the route you take and a variety of other factors.

## Important Factors

There are typically four factors when considering a more precise flight duration to any astronomical object:

• Whether or not the spacecraft is sent to other celestial objects either for scientific studies and/or gravity assist using a slingshot flight maneuver. While a quick flyby mainly for a gravity assist will dramatically increase speed and decrease travel time, time spent studying that planetary system becomes a little more complicated in terms of its actual impact on average velocity and travel time.
• The launch vehicle capabilities as much of the speed of the aircraft (disregarding gravity assists and thruster adjustments) will be determined by the speed the rocket can attain after escaping Earth’s gravity, which requires a minimum of 7 miles/ 11.2 kilometers per second (25,000 mph or just over 40,000 km/ hr) just to reach Earth’s escape velocity. As a baseline, the Apollo spacecraft reached a speed of 8 km/sec.
• Slowing down requires time by either reverse-firing thrusters in space or utilizing atmospheric re-entry if landing. A flyby will be shorter than an orbit insertion (which is the best we can do for the Sun and many other destinations like our gas giants) or landing on the surface of an object like a moon. Even more so than other destinations, a significant amount of effort, time, and fuel is spent on NOT being sucked into the Sun (unless that is the goal). The Sun is the biggest thing around, holding everything in the Solar System in place. Its gravitational pull is massive.
• An astronomical destination is not a fixed point in space like a house since it is constantly moving. Planets and other objects in the solar system move around the Sun and the Sun moves around the galaxy (we are never truly still). So, we can’t only plan to reach the end destination based on the distance when we launch, but where it will be by the time we reach it. This calculation also has to be done for any gravity assists that will be planned along the trip.

While theoretical flight plans are helpful, what real flight plans can we compare to better understand more realistic travel times to the Sun?

## Past missions to the Sun

Many of the spacecraft that study the Sun do not go to the Sun. For example, while the Solar and Heliospheric Observatory (SOHO) is the longest-running solar observatory to date, it sits at LaGrange Point 1, not even halfway to the Sun from Earth as it provides an uninterrupted view of the Sun.

However, we have sent five missions to the Sun.

### Helios

Helios-A and Helios-B (renamed Helios 1 and Helios 2 after launch) were a pair of probes launched into orbit around the Sun to study our star. It was a joint venture between German Aerospace Center (DLR) and NASA. The project set a maximum speed record for spacecraft of 157,078 mph (252,792 km/h or 70,220 m/s).

Helios-A was launched on the first operational flight of the Titan IIIE rocket and the same procedure was used for Helios-B. There were several instrumental issues for Helios-A so multiple adjustments were made to Helios-B to address these concerns. Today they are no longer functional, but remain in orbit around the Sun. Below are key mission events:

 Date(s) Event Notes December 10, 1974 Helios-A/ Helios 1 launch Late February 1975 1st perihelion 28,900,000 miles (46,500,000 km) from the Sun September 21, 1975 Second pass Temperatures of 270 F (132 C) affected certain instruments February 10, 1986 last telemetry data received After other instrumental failures January 15, 1976 Helios-B/ Helios 2 launch April 17, 1976 Closest approach 1,900,000 miles (3,000,000 km) closer to the Sun than Helios-A at a record distance of 26,987,000 mi (43.432 million km), closer than the orbit of Mercury, at a record heliocentric speed of 70 kilometres per second (250,000 km/h; 160,000 mph) March 3, 1980 Radio transceiver on Helios-B failed January 7, 1981 stop command was sent to prevent possible radio interference during future missions

Helios-A took less than three months from launch to the first perihelion while Helios-B took just about three months. Neither used flybys.

### Ulysses

Ulysses was a joint ESA-NASA mission designed to study and explore the solar poles in three dimensions. The mission originally planned to utilize two spacecraft, one from ESA and one from NASA, each of which would have flown over opposite poles and was dubbed the International Solar Polar Mission (ISPM). However, NASA canceled its spacecraft and instead focused on providing instruments, the launch vehicle, and communications and tracking.

Ulysses completed nearly three complete orbits of the Sun during more than 18 years in service and was the first mission to survey the space environment above and below the poles of our Sun. The 818-pound (371-kilogram) Ulysses spacecraft launched from the Space Shuttle Discovery.

 Date(s) Event Notes Oct. 6, 1990 Launch Escape velocity was about 10 miles per second (15.4 kilometers per second), higher than had been achieved by either of the Voyagers or Pioneers, and the fastest velocity ever achieved by a human-made object at the time July 8, 1991 Midcourse correction Feb 8, 1992 Arrived at Jupiter Ulysses became the fifth spacecraft to reach Jupiter (for 17-day observation and gravity assist) Mid 1993 Entered Sun’s solar pole region of space Jun 26-Nov 6, 1994 Observations of Sun’s south pole March 5, 1995 Passed Solar Equator Jun 19 and Sep 30, 1995 Passed over Sun’s north polar regions Mar 12, 1995 Closest approach to Sun (about 124 million miles or 200 million kilometers) Oct 1, 1995 ESA extended Ulysses’ mission and renamed it Second Solar Orbit September 2000-January 2001 Second pass over South Pole September-December 2001 second pass over North Pole (during the Sun’s peak of its 11-year cycle) June 2000 Mission extended again 2003-2004 Aphelion observations of Jupiter 2007-2008 4th extension mission of solar poles Jun 30, 2009 Loss of contact with spacecraft

From launch in October 1990 to the beginning of observations in June 1994, Ulysses took 3 years and 8 months, though many count it reaching the region of space around it a year earlier.

It’s also important to remember its closest approach was in March 1995 so we have to consider what qualifies as “arriving at the Sun”. Ulysses first did a gravity assist at Jupiter, accounting for the extended time period.

### Parker Solar Probe

Often known as the mission to “touch the Sun”, Parker Solar Probe is focused on revolutionizing our understanding of our star over the course of 24 orbits around the Sun. The Solar Probe Plus Spacecraft at 1,510 pounds (685 kilograms) at launch sat on top of a Delta IV-Heavy with Upper Stage launch vehicle.

The mission’s route will utilize seven Venus flybys over nearly seven years to gradually shrink its orbit around the Sun. Check out this animation of the Parker Solar Probe’s orbits around the Sun

Below are key dates in the mission, separated by year for easier reading. Note that perihelion means the point in an orbit that is closest to the Sun (think “peri” like perimeter or perilous or p for proximity) while aphelion is the point in an orbit that is furthest away.

 Date(s) Event Notes Aug. 12, 2018 Launch Oct. 3, 2018 1st Venus Venus Flyby Nov. 5, 2018 First Perihelion January 19, 2019 Aphelion #1 January 20, 2019 Second Orbit Begins April 4, 2019 Perihelion #2 September 1, 2019 Perihelion #3 December 26, 2019 Venus Flyby #2 January 29, 2020 Perihelion #4 June 7, 2020: Perihelion #5 July 11, 2020: Venus Flyby #3 September 27, 2020 Perihelion #6 January 17, 2021 Perihelion #7 February 20, 2021 Venus Flyby #4 April 29, 2021 Perihelion #8 August 9, 2021 Perihelion #9 October 16, 2021 Venus Flyby #5 November 21, 2021 Perihelion #10 Dec. 14, 2021 flew through the Sun’s upper atmosphere – the corona – and sampled particles and magnetic fields the first time in history, a spacecraft had touched the Sun February 25, 2022 Perihelion #11 June 1, 2022 Perihelion #12 September 6, 2022 Perihelion #13 December 11, 2022 Perihelion #14 March 17, 2023 Perihelion #15 June 22, 2023 Perihelion #16 August 21, 2023 Venus Flyby #6 Coming up in just a few days as of this publication! September 27, 2023 Perihelion #17 December 29, 2023 Perihelion #18 March 30, 2024 Perihelion #19 June 30, 2024 Perihelion #20 September 30, 2024 Perihelion #21 November 6, 2024: Venus Flyby #7 Final Venus Flyby December 24, 2024 Perihelion #22 First Close Approach March 22, 2025 Perihelion #23 June 19, 2025 Perihelion #24

In August 2023, Parker’s current speed is about 32,508 mph (52,315 kph) and since it is currently heading toward Venus for its sixth flyby, its current distance from the Sun is quite far: at over 69,191,441 miles (111,352,830 km).

At its closest approach in 2025, it will come as close as 3.83 million miles (6.16 million kilometers) to the Sun, a tenth of the orbit of Mercury, (on average, about 36 million miles from the Sun), and about seven times closer than the current record holder (the Helios 2 spacecraft, which came within 27 million miles in 1976).

At this point, it will zip around the Sun at approximately 430,000 mph (700,000 kph), fast enough to travel from Philadelphia to Washington, D.C., in one second. Its orbit will be 88 days. 8.92 miles per second (14.35 km/s)

The first perihelion was achieved only three months after launch, even including a Venus flyby in contrast to the Helios crafts.

### Solar Orbiter

Solar Orbiter is a joint ESA and NASA mission delving into the conundrum of how the Sun creates and controls the ever-changing space environment throughout our solar system by studying the heliosphere, the bubble of charged particles and magnetic fields blown out to over twice the distance to Pluto.

Over the course of 22 orbits around the Sun, it is traveling as close as 26 million miles (42 million km) from the Sun to study the magnetic fields, waves, energetic particles, and plasma escaping the Sun. It launched on a United Launch Alliance Atlas V 411 rocket, utilized multiple gravity assists from Earth and Venus, and then about 3.5 years later entered an elliptical orbit around the Sun, completing one revolution every 168 days.

It is using gravity assists from Venus and Earth to gradually lift itself out of the ecliptic plane that all the planets lie in up to an angle of about 24 degrees above the solar equator (33 degrees if the extended mission is approved) to capture the first images of the poles from high latitudes. It can hover over specific spots when it almost matches the Sun’s rate of rotation at its fastest speed.

Together with Parker Solar Probe, they are providing never before seen data to help us better understand our star.

 Date(s) Event Notes Feb. 9/10, 2020 Launch Delayed a few times from an original July 2017 estimate Late May/ eary June 2020 Crossed through tails of Comet ATLAS June 2020 1st perihelion; Captured the closest images of the Sun ever taken Within 48,000,000 miles (77,000,000 km) of the Sun July 2020 1st images released December 2020 1st Venus flyby February 2021 Closest approach within 0.5 AU, about 25 million miles (40 million kilometers) of the Sun August 9, 2021 Venus Flyby BepiColombo also did a Venus flyby just 33 hours later, making it the first “double Venus flyby” November 27, 2021 Earth flyby and Routine science operations/ main mission began March 2022 Second perihelion; Highest resolution image of the Sun’s full disc and corona ever taken September 2022 Third Venus flyby; Solves the magnetic switchback (sudden reversals in the magnetic field of solar wind) mystery October 2022 Closest Approach within 0.3 AU February 2025 Venus gravity assist March 2025 First Solar polar pass December 2026 Venus gravity assist; expected start of extended mission January 2027 Solar Polar Pass March 2028 Venus gravity assist April 2028 Solar Polar Pass June 2029 Venus gravity assist July 2029 Solar Polar Pass September 2030 Venus gravity assist

From launch to first perihelion, Solar Orbiter took 4 months to arrive at the Sun.

## General Estimate for Probes

As we have seen, you can reach 1st perihelion in orbit in 3 months, even with a Venus flyby. Subsequent gravity assists over months and even years are typically used to get closer and closer without getting sucked into the star.

## Theoretical Estimates

What about humans traveling to the Sun? It’s important to note that currently there is no safe way to send a crewed mission to the Sun or even Mercury. The temperatures and radiation threats are too high. In completely theoretical terms, the fastest that humans have ever traveled in space is 24,791 mph (39,897 km/ hr), which was achieved by the returning Apollo 10 astronauts in May 1969. At that speed, we could theoretically reach the Sun in about 155 days or about five months, but that wouldn’t include the time needed to slow down.

In terms of light speed, light from the sun takes about 8 minutes and twenty seconds to reach the Earth, so if in the future we could travel at the speed of light, which the current understanding of physics says is an impossibility for anything besides light, it would take less than 8 and a half minutes.

## Conclusion

The Sun sits about 92,955,807 miles (149,597,870 kilometers) away. The calculation for how long it would take to get there is highly dependent on the speed achieved, the route, the number of “stops”, the number of gravity assists, and the approach procedure in which we slow down. Do we go straight to the Sun or utilize gravity-assist maneuvers from other planets, especially to save on fuel?

Based on past and current missions to our star, it takes probes about 3-4 months to “arrive” at a first perihelion in orbit. However, subsequent gravity assists are often utilized to get us closer and closer. It is important to remember that crewed missions to the Sun are not considered viable due to radiation concerns (even Mercury is a no-go for humans), but who knows what innovations the future may hold? Perhaps someday in the future, we can protect astronauts in a spacecraft enough to have them visit inside Mercury’s orbit or even closer to the Sun.

#### Written by Sarah Hoffschwelle

Sarah Hoffschwelle is a freelance writer who covers a combination of topics including astronomy, general science and STEM, self-development, art, and societal commentary. In the past, Sarah worked in educational nonprofits providing free-choice learning experiences for audiences ages 2-99. As a lifelong space nerd, she loves sharing the universe with others through her words. She currently writes on Medium at https://medium.com/@sarah-marie and authors self-help and children’s books.

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