Explore the galactic map that could guide aliens to Earth

To potentially help extraterrestrials locate Earth, a pulsar map was first sent into space in 1972 attached to Pioneer 10. That spacecraft is still traveling on to the stars, but time and space are taking a toll on the cosmic coordinates it carries. The map gets increasingly unreliable as the galaxy rotates and our sun and its reference pointspulsars, the spinning cores of collapsed starschange their relative positions. So one astronomer, Scott Ransom, is proposing a new map to overcome these weaknesses.

BY MATTHEW W. CHWASTYK & DIANA MARQUES

The original map contained four elements

An atomic hydrogen diagram marks a 21-cm distance.

Old pulsar map

Human figures are shown to scale in front of the Pioneer spacecraft.

Pioneer’s trajectory is shown on a solar system diagram.

What is a pulsar?

After a supernovathe titanic explosion of a massive starthe star’s core can become incredibly dense. It is called a “pulsar” if it’s set spinning, emitting radio waves that appear to pulse on and off like a lighthouse.

The Crab Nebula is a supernova remnant with a pulsar at its core.

To make a new map,

start with stable signposts

If a small, dense pulsar is paired with another star, it siphons material and energy from its companion, accelerating the pulsar’s already rapid rotation.

At up to 43,000 rotations per minute, the radiation appears to pulse and acts like a beacon. This system is a reliable signpost for mapping within the Milky Way.

Millisecond pulsar

Magnetic

field

Companion

white dwarf star

Radiation

beam

Pulsar

rotation

System rotation

Then, add reference points

Much like how the Global Positioning System (GPS) works on Earth, these galactic beacons could provide a map to the sun. By identifying these specific pulsars and how much their

spins have changed, you reveal the sun’s location—and Earth is right nearby.

Earth orbital plane

Pulsar 1

Outer planetary orbit

Inner

solar

system

Pulsar 2

Pulsar 3

Finally, add a universal ruler

Our measurements of time and distance would be unfamiliar

to aliens. Hydrogen is a good universal alternative. When a hydrogen electron flips the direction of its spin, it emits a radio wave with a wavelength

of about 21 centimeters, the distance light travels in just

over 0.7 nanoseconds.

Spins are parallel

Hydrogen atom

Proton

Electron

21-cm

wavelength radiation

Spins are antiparallel

The new map

These new coordinates might

more accurately guide extrater-

restrial life to Earth for the next

billion years or so. Both more

distant and relatively closer guide

pulsars are used. The map

encodes how quickly rapidly

spinning pulsars rotate (rotational

periods) and how quickly star-

pulsar systems revolve around

each other (orbital periods).

DISTANT Pulsars

|--||--|-|--|-|--|-|||-X-|-||-||--|||-|-|-|-|-|-||||--||

47 Tucanae

(two binary pulsars)

|---|-||--|-|---|||--|-X-||-|-----||-|-|-|-||---|-|-|

|-----|||--|-|------||---|--||||-|--|----|---|---

|||||-|||||--||--||----|-|||-----|-----|||-|||--

Terzan 5

(two binary

pulsars)

|-|||-||||-|-|||||||-|||X|--||-|-||||--|--|-|---|||

|-|-||-----||--||-|-|-||----|||-|--|||---|---

||--||||-||-|-||||-|-|-|X|||||||-|||--|--|||---|--|||

NGC 1851

(one binary pulsar)

|--|-|----||-|---||------|------||-------|---|--

||-||----|-|-|--------|X|--||---|||-|||-||-|------|-||

|-----||----|-|||--|||-||-|-||--||--||-||||||||-----

|||---|--|||--|||--|||-||--||||-|--|--||--||-|--

|----|||--|-|-||-||--||X-||-|-||--|-|---|-||-||-||-||

||--|--|-||--||--|--||X--|---||-||---||---||-||-|-||

Near Pulsars

|----|-------|||-|--|-|-|||-|-||-||--|-||-|-||||-

|---||--|---|--|-|||||-||||--||||||--|-|-|---|--

|--||---|||-|||-|-|||-|X-||-|------|||||--||---|||||-|

J0218+4232

Messier 13

(two binary

pulsars)

Near Pulsars

|---|---|--|-|---|----|X-|-|---||||-----|||--|||--|||

||||--|--||--|----||-----||--|--------||-||||-|---

J1614-2230

J0614-3329

|---|----|||||--|---|--X-||---|||--||--||--------|||

|-|||-|-|||--|||--||------|--|--|--|-|-||||--||------

J2043+1711

||--|||--|-|--|-|-|--|X|-||-||-|-|--|-||-||-|-|--||

|-|--|-|-|||--|-|-----||||-|-|-|---|||--|-|||---

Binary ( | = 1 or - = 0, X=decimal point)

encoding for the rotational period of the pulsar and orbital period of the star pair in units of time based on the hydrogen wavelength

|||---|--|||--|||--|||-||--||||-|--|--||--||-|--

||--|--|-||--||--|--||X--|---||-||---||---||-||-|-||

J0218+4232

SEAN MCNAUGHTON; NEW PULSAR MAP: SCOTT RANSOM; MILKY WAY: ANTOINE COLLIGNON

SOURCES: NASA GODDARD SPACE FLIGHT CENTER; NATIONAL RADIO ASTRONOMY OBSERVATORY; HARVARD-SMITHSONIAN CENTER FOR ASTROPHYSICS

READ THE FULL STORY

Explore the galactic map that could guide aliens to Earth

To potentially help extraterrestrials locate Earth, a pulsar map

was first sent into space in 1972 attached to Pioneer 10. That

spacecraft is still traveling on to the stars, but time and space are

taking a toll on the cosmic coordinates it carries. The map gets

increasingly unreliable as the galaxy rotates and our sun and its

reference pointspulsars, the spinning cores of collapsed

starschange their relative positions. So one astronomer, Scott

Ransom, is proposing a new map to overcome these weaknesses.

BY MATTHEW W. CHWASTYK & DIANA MARQUES

The original map

Atomic hydrogen diagram marks a 21-cm distance.

Human figures are shown to scale in front of the Pioneer spacecraft.

Old pulsar map

Pioneer’s trajectory is shown on this solar system diagram.

What is a pulsar?

After a supernovathe titanic explosion of a massive starthe star’s core can become incredibly dense. It is called a “pulsar” if it’s set spinning, emitting radio waves that appear to pulse on and off like a lighthouse.

The Crab Nebula is a supernova remnant with a pulsar at its core.

To make a new map, start with stable signposts

If a small, dense pulsar is paired with another star, it siphons material and energy from its companion, accelerating the pulsar’s already rapid rotation. At up to 43,000 rotations per minute, the radiation appears to pulse and acts like a beacon. This system is a reliable signpost for mapping within the Milky Way.

Millisecond pulsar

Magnetic

field

Companion

white dwarf star

Radiation

beam

Pulsar

rotation

System rotation

Then, add reference points

Much like how the Global Positioning System (GPS) works on Earth, these galactic beacons could provide a map to the sun. By identifying these specific pulsars and how much their spins have changed, you reveal the sun’s locationand Earth is right nearby.

Pulsar 1

Outer planetary orbit

Pulsar 2

Inner

solar

system

Pulsar 3

Finally, add a universal ruler

Our measurements of time and distance would be unfamiliar to aliens. Hydrogen is a good universal alternative. When a hydrogen electron flips the direction of its spin, it emits a radio wave with a wavelength of about 21 centimeters, the distance light travels in just over 0.7 nanoseconds.

Spins are parallel

Hydrogen atom

Proton

Electron

21-cm

wavelength radiation

Spins are antiparallel

The new map

These new coordinates might more accurately guide extraterrestrial life to Earth for the next billion years or so. Both more distant and relatively closer guide pulsars are used. The map encodes how quickly rapidly spinning pulsars rotate (rotational periods) and how quickly star-pulsar systems revolve around each other (orbital periods).

DISTANT Pulsars

|--||--|-|--|-|--|-|||-X-|-||-||--|||-|-|-|-|-|-||||--||

47 Tucanae

(two binary pulsars)

|---|-||--|-|---|||--|-X-||-|-----||-|-|-|-||---|-|-|

|-----|||--|-|------||---|--||||-|--|----|---|---

|||||-|||||--||--||----|-|||-----|-----|||-|||--

Terzan 5

(two binary pulsars)

|-|||-||||-|-|||||||-|||X|--||-|-||||--|--|-|---|||

|-|-||-----||--||-|-|-||----|||-|--|||---|---

||--||||-||-|-||||-|-|-|X|||||||-|||--|--|||---|--|||

|--|-|----||-|---||------|------||-------|---|--

NGC 1851

(one binary pulsar)

||-||----|-|-|--------|X|--||---|||-|||-||-|------|-||

|-----||----|-|||--|||-||-|-||--||--||-||||||||-----

Messier 13

(two binary pulsars)

|||---|--|||--|||--|||-||--||||-|--|--||--||-|--

|----|||--|-|-||-||--||X-||-|-||--|-|---|-||-||-||-||

||--|--|-||--||--|--||X--|---||-||---||---||-||-|-||

Near Pulsars

|----|-------|||-|--|-|-|||-|-||-||--|-||-|-||||-

|---||--|---|--|-|||||-||||--||||||--|-|-|---|--

|--||---|||-|||-|-|||-|X-||-|------|||||--||---|||||-|

J0218+4232

|---|---|--|-|---|----|X-|-|---||||-----|||--|||--|||

||||--|--||--|----||-----||--|--------||-||||-|---

Near Pulsars

J1614-2230

J0614-3329

|---|----|||||--|---|--X-||---|||--||--||--------|||

|-|||-|-|||--|||--||------|--|--|--|-|-||||--||------

||--|||--|-|--|-|-|--|X|-||-||-|-|--|-||-||-|-|--||

J2043+1711

|-|--|-|-|||--|-|-----||||-|-|-|---|||--|-|||---

Binary ( | = 1 or - = 0, X=decimal point)

encoding for the rotational period of

the pulsar and orbital period of the

star pair in units of time based on the

hydrogen wavelength

|||---|--|||--|||--|||-||--||||-|--|--||--||-|--

||--|--|-||--||--|--||X--|---||-||---||---||-||-|-||

J0218+4232

Earth in the Milky Way

This rendering shows how the mapped

pulsars relate to our solar system.

270°

240°

300°

210°

Terzan 5

19,200 LY

30°

below

galactic

plane

Terzan 5

19,200 LY

Core

Messier 13

(NGC 6205)

23,100 light-years

(LY) from the sun

J1614-2230

2,100 LY

60°

47 Tucanae

(NGC 104)

14,700 LY

Messier 13

(NGC 6205)

23,100 light-years

(LY) from the sun

SOLAR SYSTEM

NGC 1851

39,500 LY

J2043+1711

4,500 LY

J0614-3329

2,000 LY

J0614-3329

2,000 LY

above

galactic

plane

90°

Direction of

galactic rotation

J0218+4232

10,300 LY

120°

150°

Millisecond pulsar

(pulsar with a rotational period

measured in fractions of a second)

Globular cluster containing

millisecond pulsar

SEAN MCNAUGHTON; NEW PULSAR MAP: SCOTT RANSOM; MILKY WAY: ANTOINE COLLIGNON

SOURCES: NASA GODDARD SPACE FLIGHT CENTER; NATIONAL RADIO ASTRONOMY OBSERVATORY; HARVARD-SMITHSONIAN CENTER FOR ASTROPHYSICS

READ THE FULL STORY

Explore the galactic map that could guide aliens to Earth

To potentially help extraterrestrials locate Earth, a pulsar map was first

sent into space in 1972 attached to Pioneer 10. That spacecraft is still

traveling on to the stars, but time and space are taking a toll on the cosmic

coordinates it carries. The map gets increasingly unreliable as the galaxy

rotates and our sun and its reference pointspulsars, the spinning cores of

collapsed starschange their relative positions. So one astronomer, Scott

Ransom, is proposing a new map to overcome these weaknesses.

BY MATTHEW W. CHWASTYK & DIANA MARQUES

The original map

Atomic hydrogen diagram marks a 21-cm distance.

Human figures are shown to scale in front of the Pioneer spacecraft.

Old pulsar map

Pioneer’s trajectory is shown on this solar system diagram.

What is a pulsar?

After a supernovathe titanic explosion of a massive starthe star’s core can become incredibly dense. It is called a “pulsar” if it’s set spinning, emitting radio waves that appear to pulse on and off like a lighthouse.

The Crab Nebula

is a supernova remnant with a pulsar at its core.

To make a new map, start with stable signposts

If a small, dense pulsar is paired with another star, it siphons material and energy from its companion, accelerating the pulsar’s already rapid rotation. At up to 43,000 rotations per minute, the radiation appears to pulse and acts like a beacon. This system is a reliable signpost for mapping within the Milky Way.

Millisecond pulsar

Magnetic

field

Companion

white dwarf star

Radiation

beam

Pulsar

rotation

System rotation

Then, add reference points

Much like how the Global Positioning System (GPS) works on Earth, these galactic beacons could provide a map to the sun. By identifying these specific pulsars and how much their spins have changed, you reveal the sun’s locationand Earth is right nearby.

Pulsar 1

Outer planetary orbit

Pulsar 2

Inner

solar

system

Pulsar 3

Finally, add a universal ruler

Our measurements of time and distance would be unfamiliar to aliens.

Hydrogen is a good universal alternative. When a hydrogen electron flips

the direction of its spin, it emits a radio wave with a wavelength of about

21 centimeters, the distance light travels in just over 0.7 nanoseconds.

Spins are parallel

Hydrogen atom

Proton

Electron

21-cm

wavelength radiation

Spins are antiparallel

The new map

These new coordinates might more accurately guide extraterrestrial life to Earth for the next billion years or so. Both more distant and relatively closer guide pulsars are used. The map encodes how quickly rapidly spinning pulsars rotate (rotational periods) and how quickly star-pulsar systems revolve around each other (orbital periods).

DISTANT Pulsars

|--||--|-|--|-|--|-|||-X-|-||-||--|||-|-|-|-|-|-||||--||

47 Tucanae

(two binary pulsars)

|---|-||--|-|---|||--|-X-||-|-----||-|-|-|-||---|-|-|

|-----|||--|-|------||---|--||||-|--|----|---|---

|||||-|||||--||--||----|-|||-----|-----|||-|||--

Terzan 5

(two binary pulsars)

|-|||-||||-|-|||||||-|||X|--||-|-||||--|--|-|---|||

|-|-||-----||--||-|-|-||----|||-|--|||---|---

||--||||-||-|-||||-|-|-|X|||||||-|||--|--|||---|--|||

|--|-|----||-|---||------|------||-------|---|--

NGC 1851

(one binary pulsar)

||-||----|-|-|--------|X|--||---|||-|||-||-|------|-||

|-----||----|-|||--|||-||-|-||--||--||-||||||||-----

Messier 13

(two binary pulsars)

|||---|--|||--|||--|||-||--||||-|--|--||--||-|--

|----|||--|-|-||-||--||X-||-|-||--|-|---|-||-||-||-||

||--|--|-||--||--|--||X--|---||-||---||---||-||-|-||

Near Pulsars

|----|-------|||-|--|-|-|||-|-||-||--|-||-|-||||-

|---||--|---|--|-|||||-||||--||||||--|-|-|---|--

|--||---|||-|||-|-|||-|X-||-|------|||||--||---|||||-|

J0218+4232

|---|---|--|-|---|----|X-|-|---||||-----|||--|||--|||

||||--|--||--|----||-----||--|--------||-||||-|---

Near Pulsars

J1614-2230

J0614-3329

|---|----|||||--|---|--X-||---|||--||--||--------|||

|-|||-|-|||--|||--||------|--|--|--|-|-||||--||------

||--|||--|-|--|-|-|--|X|-||-||-|-|--|-||-||-|-|--||

J2043+1711

|-|--|-|-|||--|-|-----||||-|-|-|---|||--|-|||---

Binary ( | = 1 or - = 0, X=decimal point)

encoding for the rotational period of

the pulsar and orbital period of the

star pair in units of time based on the

hydrogen wavelength

|||---|--|||--|||--|||-||--||||-|--|--||--||-|--

||--|--|-||--||--|--||X--|---||-||---||---||-||-|-||

J0218+4232

Earth in the Milky Way

This rendering shows how the mapped

pulsars relate to our solar system.

270°

240°

300°

210°

Terzan 5

19,200 LY

30°

below

galactic

plane

Terzan 5

19,200 LY

Core

Messier 13

(NGC 6205)

23,100 light-years

(LY) from the sun

J1614-2230

2,100 LY

60°

47 Tucanae

(NGC 104)

14,700 LY

Messier 13

(NGC 6205)

23,100 light-years

(LY) from the sun

WE ARE HERE

SOLAR SYSTEM

NGC 1851

39,500 LY

J2043+1711

4,500 LY

J0614-3329

2,000 LY

J0614-3329

2,000 LY

above

galactic

plane

90°

Direction of

galactic rotation

J0218+4232

10,300 LY

120°

150°

Millisecond pulsar

(pulsar with a rotational period

measured in fractions of a second)

Globular cluster containing

millisecond pulsar

SEAN MCNAUGHTON; NEW PULSAR MAP: SCOTT RANSOM; MILKY WAY: ANTOINE COLLIGNON

SOURCES: NASA GODDARD SPACE FLIGHT CENTER; NATIONAL RADIO ASTRONOMY OBSERVATORY; HARVARD-SMITHSONIAN CENTER FOR ASTROPHYSICS

READ THE FULL STORY

Explore the galactic map that could guide aliens to Earth

To potentially help extraterrestrials locate Earth, a pulsar map was first sent into space in 1972 attached to Pioneer 10. That spacecraft is still traveling on to the stars, but time and space are taking a toll on the cosmic coordinates it carries. The map gets increasingly unreliable as the galaxy rotates and our sun and its reference points—pulsars, the spinning cores of collapsed stars—change their relative positions. So one astronomer, Scott Ransom, is proposing a new map to overcome these weaknesses.

BY MATTHEW W. CHWASTYK & DIANA MARQUES

The original map

Atomic hydrogen diagram marks a 21-cm distance.

Human figures are shown to scale in front of the Pioneer spacecraft.

Old pulsar map

Pioneer’s trajectory is shown on this solar system diagram.

What is a pulsar?

After a supernovathe titanic explosion of a

massive starthe star’s core can become

incredibly dense. It is called a “pulsar” if it’s

set spinning, emitting radio waves that

appear to pulse on and off like a lighthouse.

The Crab Nebula

is a supernova remnant

with a pulsar at its core.

To make a new map, start with stable signposts

Millisecond pulsar

If a small, dense pulsar is paired with

another star, it siphons material and

energy from its companion, accelerating

the pulsar’s already rapid rotation. At up

to 43,000 rotations per minute, the

radiation appears to pulse and acts like a

beacon. This system is a reliable signpost

for mapping within the Milky Way.

Magnetic

field

Companion

white dwarf star

Radiation

beam

Pulsar

rotation

System rotation

Then, add reference points

Pulsar 1

Much like how the Global Positioning System (GPS) works on Earth, these galactic beacons could provide a map to the sun. By identifying these specific pulsars and how much their spins have changed, you reveal the sun’s locationand Earth is right nearby.

Outer planetary orbit

Pulsar 2

Inner

solar

system

Pulsar 3

Finally, add a universal ruler

Spins are parallel

Hydrogen atom

Our measurements of time and distance would be

unfamiliar to aliens. Hydrogen is a good universal

alternative. When a hydrogen electron flips the

direction of its spin, it emits a radio wave with a

wavelength of about 21 centimeters, the distance

light travels in just over 0.7 nanoseconds.

Proton

Electron

21-cm

wavelength radiation

Spins are antiparallel

|---|---|--|-|---|----|X-|-|---||||-----|||--|||--|||

||||--|--||--|----||-----||--|--------||-||||-|---

The new map

These new coordinates might more accurately guide

extraterrestrial life to Earth for the next billion years

or so. Both more distant and relatively closer guide

pulsars are used. The map encodes how quickly

rapidly spinning pulsars rotate (rotational periods)

and how quickly star-pulsar systems revolve around

each other (orbital periods).

Near Pulsars

J1614-2230

J0614-3329

|---|----|||||--|---|--X-||---|||--||--||--------|||

|-|||-|-|||--|||--||------|--|--|--|-|-||||--||------

||--|||--|-|--|-|-|--|X|-||-||-|-|--|-||-||-|-|--||

J2043+1711

|-|--|-|-|||--|-|-----||||-|-|-|---|||--|-|||---

Binary ( | = 1 or - = 0, X=decimal

point) encoding for the rota-

tional period of the pulsar and

orbital period of the star pair in

units of time based on the

hydrogen wavelength

|||---|--|||--|||--|||-||--||||-|--|--||--||-|--

||--|--|-||--||--|--||X--|---||-||---||---||-||-|-||

DISTANT Pulsars

|--||--|-|--|-|--|-|||-X-|-||-||--|||-|-|-|-|-|-||||--||

47 Tucanae

(two binary pulsars)

|---|-||--|-|---|||--|-X-||-|-----||-|-|-|-||---|-|-|

|-----|||--|-|------||---|--||||-|--|----|---|---

|||||-|||||--||--||----|-|||-----|-----|||-|||--

Terzan 5

(two binary pulsars)

|-|||-||||-|-|||||||-|||X|--||-|-||||--|--|-|---|||

|-|-||-----||--||-|-|-||----|||-|--|||---|---

||--||||-||-|-||||-|-|-|X|||||||-|||--|--|||---|--|||

|--|-|----||-|---||------|------||-------|---|--

NGC 1851

(one binary pulsar)

||-||----|-|-|--------|X|--||---|||-|||-||-|------|-||

|-----||----|-|||--|||-||-|-||--||--||-||||||||-----

Messier 13

(two binary pulsars)

|||---|--|||--|||--|||-||--||||-|--|--||--||-|--

|----|||--|-|-||-||--||X-||-|-||--|-|---|-||-||-||-||

||--|--|-||--||--|--||X--|---||-||---||---||-||-|-||

Near Pulsars

|----|-------|||-|--|-|-|||-|-||-||--|-||-|-||||-

|---||--|---|--|-|||||-||||--||||||--|-|-|---|--

|--||---|||-|||-|-|||-|X-||-|------|||||--||---|||||-|

J0218+4232

J0218+4232

Earth in the Milky Way

This rendering shows how the mapped

pulsars relate to our solar system.

300°

270°

240°

30°

Terzan 5

19,200 LY

below

galactic

plane

Core

Terzan 5

19,200 LY

Messier 13

(NGC 6205)

23,100 light-years

(LY) from the sun

210°

60°

J1614-2230

2,100 LY

Messier 13

(NGC 6205)

23,100 light-years

(LY) from the sun

47 Tucanae

(NGC 104)

14,700 LY

WE ARE HERE

SOLAR SYSTEM

above

galactic

plane

NGC 1851

39,500 LY

J2043-1711

4,500 LY

J0614-3329

2,000 LY

J0614-3329

2,000 LY

90°

Direction of

galactic rotation

180°

J0218+4232

10,300 LY

120°

Millisecond pulsar

(pulsar with a rotational period

measured in fractions of a second)

150°

Globular cluster containing

millisecond pulsar

SEAN MCNAUGHTON; NEW PULSAR MAP: SCOTT RANSOM; MILKY WAY: ANTOINE COLLIGNON

SOURCES: NASA GODDARD SPACE FLIGHT CENTER; NATIONAL RADIO ASTRONOMY OBSERVATORY; HARVARD-SMITHSONIAN CENTER FOR ASTROPHYSICS

READ THE FULL STORY